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                  \_11 |  11\ 1111111\   1111111\ 1111111\        1111\ 11 | 111111\ 111111\   11\  11\  11\  111111\   111111\  11 |  11\ 
                    11 |  11 |11  __11\ 11  _____|11  __11\       11 11\11 |11  __11\\_11  _|  11 | 11 | 11 |11  __11\ 11  __11\ 11 | 11  |
                    11 |  11 |11 |  11 |11 /      11 |  11 |      11 \1111 |11111111 | 11 |    11 | 11 | 11 |11 /  11 |11 |  \__|111111  / 
                    11 |  11 |11 |  11 |11 |      11 |  11 |      11 |\111 |11   ____| 11 |11\ 11 | 11 | 11 |11 |  11 |11 |      11  _11<  
                  111111\ 11 |11 |  11 |\1111111\ 11 |  11 |      11 | \11 |\1111111\  \1111  |\11111\1111  |\111111  |11 |      11 | \11\ 
                  \______|\__|\__|  \__| \_______|\__|  \__|      \__|  \__| \_______|  \____/  \_____\____/  \______/ \__|      \__|  \__|
                                                                                                                                           
                                                                                                                                           
                                                                                                                                           
                               111111\                                                               11\     11\                           
                              11  __11\                                                              11 |    \__|                          
                              11 /  11 | 111111\   111111\   111111\   111111\   111111\   111111\ 111111\   11\  111111\  1111111\        
                              11111111 |11  __11\ 11  __11\ 11  __11\ 11  __11\ 11  __11\  \____11\\_11  _|  11 |11  __11\ 11  __11\       
                              11  __11 |11 /  11 |11 /  11 |11 |  \__|11111111 |11 /  11 | 1111111 | 11 |    11 |11 /  11 |11 |  11 |      
                              11 |  11 |11 |  11 |11 |  11 |11 |      11   ____|11 |  11 |11  __11 | 11 |11\ 11 |11 |  11 |11 |  11 |      
                              11 |  11 |\1111111 |\1111111 |11 |      \1111111\ \1111111 |\1111111 | \1111  |11 |\111111  |11 |  11 |      
                              \__|  \__| \____11 | \____11 |\__|       \_______| \____11 | \_______|  \____/ \__| \______/ \__|  \__|      
                                        11\   11 |11\   11 |                    11\   11 |                                                 
                                        \111111  |\111111  |                    \111111  |                                                 
                                         \______/  \______/                      \______/                                                  
                                                1111111\                        11\                                                        
                                                11  __11\                       11 |                                                       
                                                11 |  11 | 111111\  11\   11\ 111111\    111111\   111111\                                 
                                                1111111  |11  __11\ 11 |  11 |\_11  _|  11  __11\ 11  __11\                                
                                                11  __11< 11 /  11 |11 |  11 |  11 |    11111111 |11 |  \__|                               
                                                11 |  11 |11 |  11 |11 |  11 |  11 |11\ 11   ____|11 |                                     
                                                11 |  11 |\111111  |\111111  |  \1111  |\1111111\ 11 |                                     
                                                \__|  \__| \______/  \______/    \____/  \_______|\__|                                     
*/

// File @openzeppelin/contracts/utils/[email protected]

// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/*
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with GSN meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address payable) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}


// File @openzeppelin/contracts/access/[email protected]



pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor () internal {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = address(0);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}


// File @openzeppelin/contracts/token/ERC20/[email protected]



pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}


// File @openzeppelin/contracts/math/[email protected]



pragma solidity >=0.6.0 <0.8.0;

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        uint256 c = a + b;
        if (c < a) return (false, 0);
        return (true, c);
    }

    /**
     * @dev Returns the substraction of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b > a) return (false, 0);
        return (true, a - b);
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) return (true, 0);
        uint256 c = a * b;
        if (c / a != b) return (false, 0);
        return (true, c);
    }

    /**
     * @dev Returns the division of two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b == 0) return (false, 0);
        return (true, a / b);
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b == 0) return (false, 0);
        return (true, a % b);
    }

    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");
        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a, "SafeMath: subtraction overflow");
        return a - b;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        if (a == 0) return 0;
        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");
        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0, "SafeMath: division by zero");
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0, "SafeMath: modulo by zero");
        return a % b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {trySub}.
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        return a - b;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryDiv}.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting with custom message when dividing by zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryMod}.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        return a % b;
    }
}


// File @openzeppelin/contracts/utils/[email protected]



pragma solidity >=0.6.2 <0.8.0;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        // solhint-disable-next-line no-inline-assembly
        assembly { size := extcodesize(account) }
        return size > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (bool success, ) = recipient.call{ value: amount }("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain`call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
      return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.call{ value: value }(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data, string memory errorMessage) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.staticcall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private pure returns(bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}


// File @openzeppelin/contracts/token/ERC20/[email protected]



pragma solidity >=0.6.0 <0.8.0;



/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using SafeMath for uint256;
    using Address for address;

    function safeTransfer(IERC20 token, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(IERC20 token, address spender, uint256 value) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        // solhint-disable-next-line max-line-length
        require((value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).add(value);
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).sub(value, "SafeERC20: decreased allowance below zero");
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
        if (returndata.length > 0) { // Return data is optional
            // solhint-disable-next-line max-line-length
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}


// File contracts/helpers/UniERC20.sol



pragma solidity ^0.6.12;


library UniERC20 {
    using SafeMath for uint256;

    IERC20 private constant _ETH_ADDRESS = IERC20(0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE);
    IERC20 private constant _ZERO_ADDRESS = IERC20(0);

    function isETH(IERC20 token) internal pure returns (bool) {
        return (token == _ZERO_ADDRESS || token == _ETH_ADDRESS);
    }

    function uniBalanceOf(IERC20 token, address account) internal view returns (uint256) {
        if (isETH(token)) {
            return account.balance;
        } else {
            return token.balanceOf(account);
        }
    }

    function uniTransfer(IERC20 token, address payable to, uint256 amount) internal {
        if (amount > 0) {
            if (isETH(token)) {
                to.transfer(amount);
            } else {
                _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, amount));
            }
        }
    }

    function uniApprove(IERC20 token, address to, uint256 amount) internal {
        require(!isETH(token), "Approve called on ETH");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = address(token).call(abi.encodeWithSelector(token.approve.selector, to, amount));

        if (!success || (returndata.length > 0 && !abi.decode(returndata, (bool)))) {
            _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, to, 0));
            _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, to, amount));
        }
    }

    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = address(token).call(data);
        require(success, "low-level call failed");

        if (returndata.length > 0) { // Return data is optional
            require(abi.decode(returndata, (bool)), "ERC20 operation did not succeed");
        }
    }
}


// File contracts/interfaces/IChi.sol



pragma solidity ^0.6.12;

interface IChi is IERC20 {
    function mint(uint256 value) external;
    function free(uint256 value) external returns (uint256 freed);
    function freeFromUpTo(address from, uint256 value) external returns (uint256 freed);
}


// File contracts/interfaces/IGasDiscountExtension.sol



pragma solidity ^0.6.12;

interface IGasDiscountExtension {
    function calculateGas(uint256 gasUsed, uint256 flags, uint256 calldataLength) external view returns (IChi, uint256);
}


// File contracts/interfaces/IAggregationExecutor.sol



pragma solidity ^0.6.12;

interface IAggregationExecutor is IGasDiscountExtension {
    function callBytes(bytes calldata data) external payable;  // 0xd9c45357
}


// File contracts/helpers/RevertReasonParser.sol



pragma solidity ^0.6.12;


library RevertReasonParser {
    function parse(bytes memory data, string memory prefix) internal pure returns (string memory) {
        // https://solidity.readthedocs.io/en/latest/control-structures.html#revert
        // We assume that revert reason is abi-encoded as Error(string)

        // 68 = 4-byte selector 0x08c379a0 + 32 bytes offset + 32 bytes length
        if (data.length >= 68 && data[0] == "\x08" && data[1] == "\xc3" && data[2] == "\x79" && data[3] == "\xa0") {
            string memory reason;
            // solhint-disable no-inline-assembly
            assembly {
                // 68 = 32 bytes data length + 4-byte selector + 32 bytes offset
                reason := add(data, 68)
            }
            /*
                revert reason is padded up to 32 bytes with ABI encoder: Error(string)
                also sometimes there is extra 32 bytes of zeros padded in the end:
                https://github.com/ethereum/solidity/issues/10170
                because of that we can't check for equality and instead check
                that string length + extra 68 bytes is less than overall data length
            */
            require(data.length >= 68 + bytes(reason).length, "Invalid revert reason");
            return string(abi.encodePacked(prefix, "Error(", reason, ")"));
        }
        // 36 = 4-byte selector 0x4e487b71 + 32 bytes integer
        else if (data.length == 36 && data[0] == "\x4e" && data[1] == "\x48" && data[2] == "\x7b" && data[3] == "\x71") {
            uint256 code;
            // solhint-disable no-inline-assembly
            assembly {
                // 36 = 32 bytes data length + 4-byte selector
                code := mload(add(data, 36))
            }
            return string(abi.encodePacked(prefix, "Panic(", _toHex(code), ")"));
        }

        return string(abi.encodePacked(prefix, "Unknown(", _toHex(data), ")"));
    }

    function _toHex(uint256 value) private pure returns(string memory) {
        return _toHex(abi.encodePacked(value));
    }

    function _toHex(bytes memory data) private pure returns(string memory) {
        bytes16 alphabet = 0x30313233343536373839616263646566;
        bytes memory str = new bytes(2 + data.length * 2);
        str[0] = "0";
        str[1] = "x";
        for (uint256 i = 0; i < data.length; i++) {
            str[2 * i + 2] = alphabet[uint8(data[i] >> 4)];
            str[2 * i + 3] = alphabet[uint8(data[i] & 0x0f)];
        }
        return string(str);
    }
}


// File contracts/interfaces/IERC20Permit.sol



pragma solidity ^0.6.12;


interface IERC20Permit {
    function permit(address owner, address spender, uint256 amount, uint256 deadline, uint8 v, bytes32 r, bytes32 s) external;
}


// File contracts/helpers/Permitable.sol



pragma solidity ^0.6.12;



contract Permitable {
    event Error(
        string reason
    );

    function _permit(IERC20 token, uint256 amount, bytes calldata permit) internal {
        if (permit.length == 32 * 7) {
            // solhint-disable-next-line avoid-low-level-calls
            (bool success, bytes memory result) = address(token).call(abi.encodePacked(IERC20Permit.permit.selector, permit));
            if (!success) {
                string memory reason = RevertReasonParser.parse(result, "Permit call failed: ");
                if (token.allowance(msg.sender, address(this)) < amount) {
                    revert(reason);
                } else {
                    emit Error(reason);
                }
            }
        }
    }
}


// File contracts/UnoswapRouter.sol



pragma solidity ^0.6.12;

contract UnoswapRouter is Permitable {
    uint256 private constant _TRANSFER_FROM_CALL_SELECTOR_32 = 0x23b872dd00000000000000000000000000000000000000000000000000000000;
    uint256 private constant _WETH_DEPOSIT_CALL_SELECTOR_32 = 0xd0e30db000000000000000000000000000000000000000000000000000000000;
    uint256 private constant _WETH_WITHDRAW_CALL_SELECTOR_32 = 0x2e1a7d4d00000000000000000000000000000000000000000000000000000000;
    uint256 private constant _ERC20_TRANSFER_CALL_SELECTOR_32 = 0xa9059cbb00000000000000000000000000000000000000000000000000000000;
    uint256 private constant _ADDRESS_MASK =   0x000000000000000000000000ffffffffffffffffffffffffffffffffffffffff;
    uint256 private constant _REVERSE_MASK =   0x8000000000000000000000000000000000000000000000000000000000000000;
    uint256 private constant _WETH_MASK =      0x4000000000000000000000000000000000000000000000000000000000000000;
    uint256 private constant _NUMERATOR_MASK = 0x0000000000000000ffffffff0000000000000000000000000000000000000000;
    uint256 private constant _WETH = 0x000000000000000000000000C02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2;
    uint256 private constant _UNISWAP_PAIR_RESERVES_CALL_SELECTOR_32 = 0x0902f1ac00000000000000000000000000000000000000000000000000000000;
    uint256 private constant _UNISWAP_PAIR_SWAP_CALL_SELECTOR_32 = 0x022c0d9f00000000000000000000000000000000000000000000000000000000;
    uint256 private constant _DENOMINATOR = 1000000000;
    uint256 private constant _NUMERATOR_OFFSET = 160;

    receive() external payable {
        // solhint-disable-next-line avoid-tx-origin
        require(msg.sender != tx.origin, "ETH deposit rejected");
    }

    function unoswapWithPermit(
        IERC20 srcToken,
        uint256 amount,
        uint256 minReturn,
        bytes32[] calldata pools,
        bytes calldata permit
    ) external payable returns(uint256 returnAmount) {
        _permit(srcToken, amount, permit);
        return unoswap(srcToken, amount, minReturn, pools);
    }

    function unoswap(
        IERC20 srcToken,
        uint256 amount,
        uint256 minReturn,
        bytes32[] calldata /* pools */
    ) public payable returns(uint256 returnAmount) {
        assembly {  // solhint-disable-line no-inline-assembly
            function reRevert() {
                returndatacopy(0, 0, returndatasize())
                revert(0, returndatasize())
            }

            function revertWithReason(m, len) {
                mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
                mstore(0x20, 0x0000002000000000000000000000000000000000000000000000000000000000)
                mstore(0x40, m)
                revert(0, len)
            }

            function swap(emptyPtr, swapAmount, pair, reversed, numerator, dst) -> ret {
                mstore(emptyPtr, _UNISWAP_PAIR_RESERVES_CALL_SELECTOR_32)
                if iszero(staticcall(gas(), pair, emptyPtr, 0x4, emptyPtr, 0x40)) {
                    reRevert()
                }

                let reserve0 := mload(emptyPtr)
                let reserve1 := mload(add(emptyPtr, 0x20))
                if reversed {
                    let tmp := reserve0
                    reserve0 := reserve1
                    reserve1 := tmp
                }
                ret := mul(swapAmount, numerator)
                ret := div(mul(ret, reserve1), add(ret, mul(reserve0, _DENOMINATOR)))

                mstore(emptyPtr, _UNISWAP_PAIR_SWAP_CALL_SELECTOR_32)
                switch reversed
                case 0 {
                    mstore(add(emptyPtr, 0x04), 0)
                    mstore(add(emptyPtr, 0x24), ret)
                }
                default {
                    mstore(add(emptyPtr, 0x04), ret)
                    mstore(add(emptyPtr, 0x24), 0)
                }
                mstore(add(emptyPtr, 0x44), dst)
                mstore(add(emptyPtr, 0x64), 0x80)
                mstore(add(emptyPtr, 0x84), 0)
                if iszero(call(gas(), pair, 0, emptyPtr, 0xa4, 0, 0)) {
                    reRevert()
                }
            }

            let emptyPtr := mload(0x40)
            mstore(0x40, add(emptyPtr, 0xc0))

            let poolsOffset := add(calldataload(0x64), 0x4)
            let poolsEndOffset := calldataload(poolsOffset)
            poolsOffset := add(poolsOffset, 0x20)
            poolsEndOffset := add(poolsOffset, mul(0x20, poolsEndOffset))
            let rawPair := calldataload(poolsOffset)
            switch srcToken
            case 0 {
                if iszero(eq(amount, callvalue())) {
                    revertWithReason(0x00000011696e76616c6964206d73672e76616c75650000000000000000000000, 0x55)  // "invalid msg.value"
                }

                mstore(emptyPtr, _WETH_DEPOSIT_CALL_SELECTOR_32)
                if iszero(call(gas(), _WETH, amount, emptyPtr, 0x4, 0, 0)) {
                    reRevert()
                }

                mstore(emptyPtr, _ERC20_TRANSFER_CALL_SELECTOR_32)
                mstore(add(emptyPtr, 0x4), and(rawPair, _ADDRESS_MASK))
                mstore(add(emptyPtr, 0x24), amount)
                if iszero(call(gas(), _WETH, 0, emptyPtr, 0x44, 0, 0)) {
                    reRevert()
                }
            }
            default {
                if callvalue() {
                    revertWithReason(0x00000011696e76616c6964206d73672e76616c75650000000000000000000000, 0x55)  // "invalid msg.value"
                }

                mstore(emptyPtr, _TRANSFER_FROM_CALL_SELECTOR_32)
                mstore(add(emptyPtr, 0x4), caller())
                mstore(add(emptyPtr, 0x24), and(rawPair, _ADDRESS_MASK))
                mstore(add(emptyPtr, 0x44), amount)
                if iszero(call(gas(), srcToken, 0, emptyPtr, 0x64, 0, 0)) {
                    reRevert()
                }
            }

            returnAmount := amount

            for {let i := add(poolsOffset, 0x20)} lt(i, poolsEndOffset) {i := add(i, 0x20)} {
                let nextRawPair := calldataload(i)

                returnAmount := swap(
                    emptyPtr,
                    returnAmount,
                    and(rawPair, _ADDRESS_MASK),
                    and(rawPair, _REVERSE_MASK),
                    shr(_NUMERATOR_OFFSET, and(rawPair, _NUMERATOR_MASK)),
                    and(nextRawPair, _ADDRESS_MASK)
                )

                rawPair := nextRawPair
            }

            switch and(rawPair, _WETH_MASK)
            case 0 {
                returnAmount := swap(
                    emptyPtr,
                    returnAmount,
                    and(rawPair, _ADDRESS_MASK),
                    and(rawPair, _REVERSE_MASK),
                    shr(_NUMERATOR_OFFSET, and(rawPair, _NUMERATOR_MASK)),
                    caller()
                )
            }
            default {
                returnAmount := swap(
                    emptyPtr,
                    returnAmount,
                    and(rawPair, _ADDRESS_MASK),
                    and(rawPair, _REVERSE_MASK),
                    shr(_NUMERATOR_OFFSET, and(rawPair, _NUMERATOR_MASK)),
                    address()
                )

                mstore(emptyPtr, _WETH_WITHDRAW_CALL_SELECTOR_32)
                mstore(add(emptyPtr, 0x04), returnAmount)
                if iszero(call(gas(), _WETH, 0, emptyPtr, 0x24, 0, 0)) {
                    reRevert()
                }

                if iszero(call(gas(), caller(), returnAmount, 0, 0, 0, 0)) {
                    reRevert()
                }
            }

            if lt(returnAmount, minReturn) {
                revertWithReason(0x000000164d696e2072657475726e206e6f742072656163686564000000000000, 0x5a)  // "Min return not reached"
            }
        }
    }
}


// File contracts/AggregationRouterV3.sol



pragma solidity ^0.6.12;
pragma experimental ABIEncoderV2;






contract AggregationRouterV3 is Ownable, UnoswapRouter {
    using SafeMath for uint256;
    using SafeERC20 for IERC20;
    using UniERC20 for IERC20;

    uint256 private constant _PARTIAL_FILL = 0x01;
    uint256 private constant _REQUIRES_EXTRA_ETH = 0x02;
    uint256 private constant _SHOULD_CLAIM = 0x04;
    uint256 private constant _BURN_FROM_MSG_SENDER = 0x08;
    uint256 private constant _BURN_FROM_TX_ORIGIN = 0x10;

    struct SwapDescription {
        IERC20 srcToken;
        IERC20 dstToken;
        address srcReceiver;
        address dstReceiver;
        uint256 amount;
        uint256 minReturnAmount;
        uint256 flags;
        bytes permit;
    }

    event Swapped(
        address sender,
        IERC20 srcToken,
        IERC20 dstToken,
        address dstReceiver,
        uint256 spentAmount,
        uint256 returnAmount
    );

    function discountedSwap(
        IAggregationExecutor caller,
        SwapDescription calldata desc,
        bytes calldata data
    )
        external
        payable
        returns (uint256 returnAmount, uint256 gasLeft, uint256 chiSpent)
    {
        uint256 initialGas = gasleft();

        address chiSource = address(0);
        if (desc.flags & _BURN_FROM_MSG_SENDER != 0) {
            chiSource = msg.sender;
        } else if (desc.flags & _BURN_FROM_TX_ORIGIN != 0) {
            chiSource = tx.origin; // solhint-disable-line avoid-tx-origin
        } else {
            revert("Incorrect CHI burn flags");
        }

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returnData) = address(this).delegatecall(abi.encodeWithSelector(this.swap.selector, caller, desc, data));
        if (success) {
            (returnAmount,) = abi.decode(returnData, (uint256, uint256));
        } else {
            if (msg.value > 0) {
                msg.sender.transfer(msg.value);
            }
            emit Error(RevertReasonParser.parse(returnData, "Swap failed: "));
        }

        (IChi chi, uint256 amount) = caller.calculateGas(initialGas.sub(gasleft()), desc.flags, msg.data.length);
        if (amount > 0) {
            chiSpent = chi.freeFromUpTo(chiSource, amount);
        }
        gasLeft = gasleft();
    }

    function swap(
        IAggregationExecutor caller,
        SwapDescription calldata desc,
        bytes calldata data
    )
        external
        payable
        returns (uint256 returnAmount, uint256 gasLeft)
    {
        require(desc.minReturnAmount > 0, "Min return should not be 0");
        require(data.length > 0, "data should be not zero");

        uint256 flags = desc.flags;
        IERC20 srcToken = desc.srcToken;
        IERC20 dstToken = desc.dstToken;

        if (flags & _REQUIRES_EXTRA_ETH != 0) {
            require(msg.value > (srcToken.isETH() ? desc.amount : 0), "Invalid msg.value");
        } else {
            require(msg.value == (srcToken.isETH() ? desc.amount : 0), "Invalid msg.value");
        }

        if (flags & _SHOULD_CLAIM != 0) {
            require(!srcToken.isETH(), "Claim token is ETH");
            _permit(srcToken, desc.amount, desc.permit);
            srcToken.safeTransferFrom(msg.sender, desc.srcReceiver, desc.amount);
        }

        address dstReceiver = (desc.dstReceiver == address(0)) ? msg.sender : desc.dstReceiver;
        uint256 initialSrcBalance = (flags & _PARTIAL_FILL != 0) ? srcToken.uniBalanceOf(msg.sender) : 0;
        uint256 initialDstBalance = dstToken.uniBalanceOf(dstReceiver);

        {
            // solhint-disable-next-line avoid-low-level-calls
            (bool success, bytes memory result) = address(caller).call{value: msg.value}(abi.encodePacked(caller.callBytes.selector, data));
            if (!success) {
                revert(RevertReasonParser.parse(result, "callBytes failed: "));
            }
        }

        uint256 spentAmount = desc.amount;
        returnAmount = dstToken.uniBalanceOf(dstReceiver).sub(initialDstBalance);

        if (flags & _PARTIAL_FILL != 0) {
            spentAmount = initialSrcBalance.add(desc.amount).sub(srcToken.uniBalanceOf(msg.sender));
            require(returnAmount.mul(desc.amount) >= desc.minReturnAmount.mul(spentAmount), "Return amount is not enough");
        } else {
            require(returnAmount >= desc.minReturnAmount, "Return amount is not enough");
        }

        emit Swapped(
            msg.sender,
            srcToken,
            dstToken,
            dstReceiver,
            spentAmount,
            returnAmount
        );

        gasLeft = gasleft();
    }

    function rescueFunds(IERC20 token, uint256 amount) external onlyOwner {
        token.uniTransfer(msg.sender, amount);
    }

    function destroy() external onlyOwner {
        selfdestruct(msg.sender);
    }
}

pragma solidity ^0.4.24;

// File: zos-lib/contracts/upgradeability/Proxy.sol

/**
 * @title Proxy
 * @dev Implements delegation of calls to other contracts, with proper
 * forwarding of return values and bubbling of failures.
 * It defines a fallback function that delegates all calls to the address
 * returned by the abstract _implementation() internal function.
 */
contract Proxy {
  /**
   * @dev Fallback function.
   * Implemented entirely in `_fallback`.
   */
  function () payable external {
    _fallback();
  }

  /**
   * @return The Address of the implementation.
   */
  function _implementation() internal view returns (address);

  /**
   * @dev Delegates execution to an implementation contract.
   * This is a low level function that doesn't return to its internal call site.
   * It will return to the external caller whatever the implementation returns.
   * @param implementation Address to delegate.
   */
  function _delegate(address implementation) internal {
    assembly {
      // Copy msg.data. We take full control of memory in this inline assembly
      // block because it will not return to Solidity code. We overwrite the
      // Solidity scratch pad at memory position 0.
      calldatacopy(0, 0, calldatasize)

      // Call the implementation.
      // out and outsize are 0 because we don't know the size yet.
      let result := delegatecall(gas, implementation, 0, calldatasize, 0, 0)

      // Copy the returned data.
      returndatacopy(0, 0, returndatasize)

      switch result
      // delegatecall returns 0 on error.
      case 0 { revert(0, returndatasize) }
      default { return(0, returndatasize) }
    }
  }

  /**
   * @dev Function that is run as the first thing in the fallback function.
   * Can be redefined in derived contracts to add functionality.
   * Redefinitions must call super._willFallback().
   */
  function _willFallback() internal {
  }

  /**
   * @dev fallback implementation.
   * Extracted to enable manual triggering.
   */
  function _fallback() internal {
    _willFallback();
    _delegate(_implementation());
  }
}

// File: openzeppelin-solidity/contracts/AddressUtils.sol

/**
 * Utility library of inline functions on addresses
 */
library AddressUtils {

  /**
   * Returns whether the target address is a contract
   * @dev This function will return false if invoked during the constructor of a contract,
   * as the code is not actually created until after the constructor finishes.
   * @param addr address to check
   * @return whether the target address is a contract
   */
  function isContract(address addr) internal view returns (bool) {
    uint256 size;
    // XXX Currently there is no better way to check if there is a contract in an address
    // than to check the size of the code at that address.
    // See https://ethereum.stackexchange.com/a/14016/36603
    // for more details about how this works.
    // TODO Check this again before the Serenity release, because all addresses will be
    // contracts then.
    // solium-disable-next-line security/no-inline-assembly
    assembly { size := extcodesize(addr) }
    return size > 0;
  }

}

// File: zos-lib/contracts/upgradeability/UpgradeabilityProxy.sol

/**
 * @title UpgradeabilityProxy
 * @dev This contract implements a proxy that allows to change the
 * implementation address to which it will delegate.
 * Such a change is called an implementation upgrade.
 */
contract UpgradeabilityProxy is Proxy {
  /**
   * @dev Emitted when the implementation is upgraded.
   * @param implementation Address of the new implementation.
   */
  event Upgraded(address implementation);

  /**
   * @dev Storage slot with the address of the current implementation.
   * This is the keccak-256 hash of "org.zeppelinos.proxy.implementation", and is
   * validated in the constructor.
   */
  bytes32 private constant IMPLEMENTATION_SLOT = 0x7050c9e0f4ca769c69bd3a8ef740bc37934f8e2c036e5a723fd8ee048ed3f8c3;

  /**
   * @dev Contract constructor.
   * @param _implementation Address of the initial implementation.
   */
  constructor(address _implementation) public {
    assert(IMPLEMENTATION_SLOT == keccak256("org.zeppelinos.proxy.implementation"));

    _setImplementation(_implementation);
  }

  /**
   * @dev Returns the current implementation.
   * @return Address of the current implementation
   */
  function _implementation() internal view returns (address impl) {
    bytes32 slot = IMPLEMENTATION_SLOT;
    assembly {
      impl := sload(slot)
    }
  }

  /**
   * @dev Upgrades the proxy to a new implementation.
   * @param newImplementation Address of the new implementation.
   */
  function _upgradeTo(address newImplementation) internal {
    _setImplementation(newImplementation);
    emit Upgraded(newImplementation);
  }

  /**
   * @dev Sets the implementation address of the proxy.
   * @param newImplementation Address of the new implementation.
   */
  function _setImplementation(address newImplementation) private {
    require(AddressUtils.isContract(newImplementation), "Cannot set a proxy implementation to a non-contract address");

    bytes32 slot = IMPLEMENTATION_SLOT;

    assembly {
      sstore(slot, newImplementation)
    }
  }
}

// File: zos-lib/contracts/upgradeability/AdminUpgradeabilityProxy.sol

/**
 * @title AdminUpgradeabilityProxy
 * @dev This contract combines an upgradeability proxy with an authorization
 * mechanism for administrative tasks.
 * All external functions in this contract must be guarded by the
 * `ifAdmin` modifier. See ethereum/solidity#3864 for a Solidity
 * feature proposal that would enable this to be done automatically.
 */
contract AdminUpgradeabilityProxy is UpgradeabilityProxy {
  /**
   * @dev Emitted when the administration has been transferred.
   * @param previousAdmin Address of the previous admin.
   * @param newAdmin Address of the new admin.
   */
  event AdminChanged(address previousAdmin, address newAdmin);

  /**
   * @dev Storage slot with the admin of the contract.
   * This is the keccak-256 hash of "org.zeppelinos.proxy.admin", and is
   * validated in the constructor.
   */
  bytes32 private constant ADMIN_SLOT = 0x10d6a54a4754c8869d6886b5f5d7fbfa5b4522237ea5c60d11bc4e7a1ff9390b;

  /**
   * @dev Modifier to check whether the `msg.sender` is the admin.
   * If it is, it will run the function. Otherwise, it will delegate the call
   * to the implementation.
   */
  modifier ifAdmin() {
    if (msg.sender == _admin()) {
      _;
    } else {
      _fallback();
    }
  }

  /**
   * Contract constructor.
   * It sets the `msg.sender` as the proxy administrator.
   * @param _implementation address of the initial implementation.
   */
  constructor(address _implementation) UpgradeabilityProxy(_implementation) public {
    assert(ADMIN_SLOT == keccak256("org.zeppelinos.proxy.admin"));

    _setAdmin(msg.sender);
  }

  /**
   * @return The address of the proxy admin.
   */
  function admin() external view ifAdmin returns (address) {
    return _admin();
  }

  /**
   * @return The address of the implementation.
   */
  function implementation() external view ifAdmin returns (address) {
    return _implementation();
  }

  /**
   * @dev Changes the admin of the proxy.
   * Only the current admin can call this function.
   * @param newAdmin Address to transfer proxy administration to.
   */
  function changeAdmin(address newAdmin) external ifAdmin {
    require(newAdmin != address(0), "Cannot change the admin of a proxy to the zero address");
    emit AdminChanged(_admin(), newAdmin);
    _setAdmin(newAdmin);
  }

  /**
   * @dev Upgrade the backing implementation of the proxy.
   * Only the admin can call this function.
   * @param newImplementation Address of the new implementation.
   */
  function upgradeTo(address newImplementation) external ifAdmin {
    _upgradeTo(newImplementation);
  }

  /**
   * @dev Upgrade the backing implementation of the proxy and call a function
   * on the new implementation.
   * This is useful to initialize the proxied contract.
   * @param newImplementation Address of the new implementation.
   * @param data Data to send as msg.data in the low level call.
   * It should include the signature and the parameters of the function to be
   * called, as described in
   * https://solidity.readthedocs.io/en/develop/abi-spec.html#function-selector-and-argument-encoding.
   */
  function upgradeToAndCall(address newImplementation, bytes data) payable external ifAdmin {
    _upgradeTo(newImplementation);
    require(address(this).call.value(msg.value)(data));
  }

  /**
   * @return The admin slot.
   */
  function _admin() internal view returns (address adm) {
    bytes32 slot = ADMIN_SLOT;
    assembly {
      adm := sload(slot)
    }
  }

  /**
   * @dev Sets the address of the proxy admin.
   * @param newAdmin Address of the new proxy admin.
   */
  function _setAdmin(address newAdmin) internal {
    bytes32 slot = ADMIN_SLOT;

    assembly {
      sstore(slot, newAdmin)
    }
  }

  /**
   * @dev Only fall back when the sender is not the admin.
   */
  function _willFallback() internal {
    require(msg.sender != _admin(), "Cannot call fallback function from the proxy admin");
    super._willFallback();
  }
}

// File: contracts/FiatTokenProxy.sol

/**
* Copyright CENTRE SECZ 2018
*
* Permission is hereby granted, free of charge, to any person obtaining a copy 
* of this software and associated documentation files (the "Software"), to deal 
* in the Software without restriction, including without limitation the rights 
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 
* copies of the Software, and to permit persons to whom the Software is furnished to 
* do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all 
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN 
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

pragma solidity ^0.4.24;


/**
 * @title FiatTokenProxy
 * @dev This contract proxies FiatToken calls and enables FiatToken upgrades
*/ 
contract FiatTokenProxy is AdminUpgradeabilityProxy {
    constructor(address _implementation) public AdminUpgradeabilityProxy(_implementation) {
    }
}

// File: @openzeppelin/contracts/math/SafeMath.sol

// SPDX-License-Identifier: MIT

pragma solidity ^0.6.0;

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return div(a, b, "SafeMath: division by zero");
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return mod(a, b, "SafeMath: modulo by zero");
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts with custom message when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol

pragma solidity ^0.6.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount)
        external
        returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender)
        external
        view
        returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(
        address indexed owner,
        address indexed spender,
        uint256 value
    );
}

// File: contracts/v1/AbstractFiatTokenV1.sol

/**
 * Copyright (c) 2018-2020 CENTRE SECZ
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

pragma solidity 0.6.12;

abstract contract AbstractFiatTokenV1 is IERC20 {
    function _approve(
        address owner,
        address spender,
        uint256 value
    ) internal virtual;

    function _transfer(
        address from,
        address to,
        uint256 value
    ) internal virtual;
}

// File: contracts/v1/Ownable.sol

/**
 * Copyright (c) 2018 zOS Global Limited.
 * Copyright (c) 2018-2020 CENTRE SECZ
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
pragma solidity 0.6.12;

/**
 * @notice The Ownable contract has an owner address, and provides basic
 * authorization control functions
 * @dev Forked from https://github.com/OpenZeppelin/openzeppelin-labs/blob/3887ab77b8adafba4a26ace002f3a684c1a3388b/upgradeability_ownership/contracts/ownership/Ownable.sol
 * Modifications:
 * 1. Consolidate OwnableStorage into this contract (7/13/18)
 * 2. Reformat, conform to Solidity 0.6 syntax, and add error messages (5/13/20)
 * 3. Make public functions external (5/27/20)
 */
contract Ownable {
    // Owner of the contract
    address private _owner;

    /**
     * @dev Event to show ownership has been transferred
     * @param previousOwner representing the address of the previous owner
     * @param newOwner representing the address of the new owner
     */
    event OwnershipTransferred(address previousOwner, address newOwner);

    /**
     * @dev The constructor sets the original owner of the contract to the sender account.
     */
    constructor() public {
        setOwner(msg.sender);
    }

    /**
     * @dev Tells the address of the owner
     * @return the address of the owner
     */
    function owner() external view returns (address) {
        return _owner;
    }

    /**
     * @dev Sets a new owner address
     */
    function setOwner(address newOwner) internal {
        _owner = newOwner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(msg.sender == _owner, "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Allows the current owner to transfer control of the contract to a newOwner.
     * @param newOwner The address to transfer ownership to.
     */
    function transferOwnership(address newOwner) external onlyOwner {
        require(
            newOwner != address(0),
            "Ownable: new owner is the zero address"
        );
        emit OwnershipTransferred(_owner, newOwner);
        setOwner(newOwner);
    }
}

// File: contracts/v1/Pausable.sol

/**
 * Copyright (c) 2016 Smart Contract Solutions, Inc.
 * Copyright (c) 2018-2020 CENTRE SECZ0
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

pragma solidity 0.6.12;

/**
 * @notice Base contract which allows children to implement an emergency stop
 * mechanism
 * @dev Forked from https://github.com/OpenZeppelin/openzeppelin-contracts/blob/feb665136c0dae9912e08397c1a21c4af3651ef3/contracts/lifecycle/Pausable.sol
 * Modifications:
 * 1. Added pauser role, switched pause/unpause to be onlyPauser (6/14/2018)
 * 2. Removed whenNotPause/whenPaused from pause/unpause (6/14/2018)
 * 3. Removed whenPaused (6/14/2018)
 * 4. Switches ownable library to use ZeppelinOS (7/12/18)
 * 5. Remove constructor (7/13/18)
 * 6. Reformat, conform to Solidity 0.6 syntax and add error messages (5/13/20)
 * 7. Make public functions external (5/27/20)
 */
contract Pausable is Ownable {
    event Pause();
    event Unpause();
    event PauserChanged(address indexed newAddress);

    address public pauser;
    bool public paused = false;

    /**
     * @dev Modifier to make a function callable only when the contract is not paused.
     */
    modifier whenNotPaused() {
        require(!paused, "Pausable: paused");
        _;
    }

    /**
     * @dev throws if called by any account other than the pauser
     */
    modifier onlyPauser() {
        require(msg.sender == pauser, "Pausable: caller is not the pauser");
        _;
    }

    /**
     * @dev called by the owner to pause, triggers stopped state
     */
    function pause() external onlyPauser {
        paused = true;
        emit Pause();
    }

    /**
     * @dev called by the owner to unpause, returns to normal state
     */
    function unpause() external onlyPauser {
        paused = false;
        emit Unpause();
    }

    /**
     * @dev update the pauser role
     */
    function updatePauser(address _newPauser) external onlyOwner {
        require(
            _newPauser != address(0),
            "Pausable: new pauser is the zero address"
        );
        pauser = _newPauser;
        emit PauserChanged(pauser);
    }
}

// File: contracts/v1/Blacklistable.sol

/**
 * Copyright (c) 2018-2020 CENTRE SECZ
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

pragma solidity 0.6.12;

/**
 * @title Blacklistable Token
 * @dev Allows accounts to be blacklisted by a "blacklister" role
 */
contract Blacklistable is Ownable {
    address public blacklister;
    mapping(address => bool) internal blacklisted;

    event Blacklisted(address indexed _account);
    event UnBlacklisted(address indexed _account);
    event BlacklisterChanged(address indexed newBlacklister);

    /**
     * @dev Throws if called by any account other than the blacklister
     */
    modifier onlyBlacklister() {
        require(
            msg.sender == blacklister,
            "Blacklistable: caller is not the blacklister"
        );
        _;
    }

    /**
     * @dev Throws if argument account is blacklisted
     * @param _account The address to check
     */
    modifier notBlacklisted(address _account) {
        require(
            !blacklisted[_account],
            "Blacklistable: account is blacklisted"
        );
        _;
    }

    /**
     * @dev Checks if account is blacklisted
     * @param _account The address to check
     */
    function isBlacklisted(address _account) external view returns (bool) {
        return blacklisted[_account];
    }

    /**
     * @dev Adds account to blacklist
     * @param _account The address to blacklist
     */
    function blacklist(address _account) external onlyBlacklister {
        blacklisted[_account] = true;
        emit Blacklisted(_account);
    }

    /**
     * @dev Removes account from blacklist
     * @param _account The address to remove from the blacklist
     */
    function unBlacklist(address _account) external onlyBlacklister {
        blacklisted[_account] = false;
        emit UnBlacklisted(_account);
    }

    function updateBlacklister(address _newBlacklister) external onlyOwner {
        require(
            _newBlacklister != address(0),
            "Blacklistable: new blacklister is the zero address"
        );
        blacklister = _newBlacklister;
        emit BlacklisterChanged(blacklister);
    }
}

// File: contracts/v1/FiatTokenV1.sol

/**
 *
 * Copyright (c) 2018-2020 CENTRE SECZ
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

pragma solidity 0.6.12;

/**
 * @title FiatToken
 * @dev ERC20 Token backed by fiat reserves
 */
contract FiatTokenV1 is AbstractFiatTokenV1, Ownable, Pausable, Blacklistable {
    using SafeMath for uint256;

    string public name;
    string public symbol;
    uint8 public decimals;
    string public currency;
    address public masterMinter;
    bool internal initialized;

    mapping(address => uint256) internal balances;
    mapping(address => mapping(address => uint256)) internal allowed;
    uint256 internal totalSupply_ = 0;
    mapping(address => bool) internal minters;
    mapping(address => uint256) internal minterAllowed;

    event Mint(address indexed minter, address indexed to, uint256 amount);
    event Burn(address indexed burner, uint256 amount);
    event MinterConfigured(address indexed minter, uint256 minterAllowedAmount);
    event MinterRemoved(address indexed oldMinter);
    event MasterMinterChanged(address indexed newMasterMinter);

    function initialize(
        string memory tokenName,
        string memory tokenSymbol,
        string memory tokenCurrency,
        uint8 tokenDecimals,
        address newMasterMinter,
        address newPauser,
        address newBlacklister,
        address newOwner
    ) public {
        require(!initialized, "FiatToken: contract is already initialized");
        require(
            newMasterMinter != address(0),
            "FiatToken: new masterMinter is the zero address"
        );
        require(
            newPauser != address(0),
            "FiatToken: new pauser is the zero address"
        );
        require(
            newBlacklister != address(0),
            "FiatToken: new blacklister is the zero address"
        );
        require(
            newOwner != address(0),
            "FiatToken: new owner is the zero address"
        );

        name = tokenName;
        symbol = tokenSymbol;
        currency = tokenCurrency;
        decimals = tokenDecimals;
        masterMinter = newMasterMinter;
        pauser = newPauser;
        blacklister = newBlacklister;
        setOwner(newOwner);
        initialized = true;
    }

    /**
     * @dev Throws if called by any account other than a minter
     */
    modifier onlyMinters() {
        require(minters[msg.sender], "FiatToken: caller is not a minter");
        _;
    }

    /**
     * @dev Function to mint tokens
     * @param _to The address that will receive the minted tokens.
     * @param _amount The amount of tokens to mint. Must be less than or equal
     * to the minterAllowance of the caller.
     * @return A boolean that indicates if the operation was successful.
     */
    function mint(address _to, uint256 _amount)
        external
        whenNotPaused
        onlyMinters
        notBlacklisted(msg.sender)
        notBlacklisted(_to)
        returns (bool)
    {
        require(_to != address(0), "FiatToken: mint to the zero address");
        require(_amount > 0, "FiatToken: mint amount not greater than 0");

        uint256 mintingAllowedAmount = minterAllowed[msg.sender];
        require(
            _amount <= mintingAllowedAmount,
            "FiatToken: mint amount exceeds minterAllowance"
        );

        totalSupply_ = totalSupply_.add(_amount);
        balances[_to] = balances[_to].add(_amount);
        minterAllowed[msg.sender] = mintingAllowedAmount.sub(_amount);
        emit Mint(msg.sender, _to, _amount);
        emit Transfer(address(0), _to, _amount);
        return true;
    }

    /**
     * @dev Throws if called by any account other than the masterMinter
     */
    modifier onlyMasterMinter() {
        require(
            msg.sender == masterMinter,
            "FiatToken: caller is not the masterMinter"
        );
        _;
    }

    /**
     * @dev Get minter allowance for an account
     * @param minter The address of the minter
     */
    function minterAllowance(address minter) external view returns (uint256) {
        return minterAllowed[minter];
    }

    /**
     * @dev Checks if account is a minter
     * @param account The address to check
     */
    function isMinter(address account) external view returns (bool) {
        return minters[account];
    }

    /**
     * @notice Amount of remaining tokens spender is allowed to transfer on
     * behalf of the token owner
     * @param owner     Token owner's address
     * @param spender   Spender's address
     * @return Allowance amount
     */
    function allowance(address owner, address spender)
        external
        override
        view
        returns (uint256)
    {
        return allowed[owner][spender];
    }

    /**
     * @dev Get totalSupply of token
     */
    function totalSupply() external override view returns (uint256) {
        return totalSupply_;
    }

    /**
     * @dev Get token balance of an account
     * @param account address The account
     */
    function balanceOf(address account)
        external
        override
        view
        returns (uint256)
    {
        return balances[account];
    }

    /**
     * @notice Set spender's allowance over the caller's tokens to be a given
     * value.
     * @param spender   Spender's address
     * @param value     Allowance amount
     * @return True if successful
     */
    function approve(address spender, uint256 value)
        external
        override
        whenNotPaused
        notBlacklisted(msg.sender)
        notBlacklisted(spender)
        returns (bool)
    {
        _approve(msg.sender, spender, value);
        return true;
    }

    /**
     * @dev Internal function to set allowance
     * @param owner     Token owner's address
     * @param spender   Spender's address
     * @param value     Allowance amount
     */
    function _approve(
        address owner,
        address spender,
        uint256 value
    ) internal override {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");
        allowed[owner][spender] = value;
        emit Approval(owner, spender, value);
    }

    /**
     * @notice Transfer tokens by spending allowance
     * @param from  Payer's address
     * @param to    Payee's address
     * @param value Transfer amount
     * @return True if successful
     */
    function transferFrom(
        address from,
        address to,
        uint256 value
    )
        external
        override
        whenNotPaused
        notBlacklisted(msg.sender)
        notBlacklisted(from)
        notBlacklisted(to)
        returns (bool)
    {
        require(
            value <= allowed[from][msg.sender],
            "ERC20: transfer amount exceeds allowance"
        );
        _transfer(from, to, value);
        allowed[from][msg.sender] = allowed[from][msg.sender].sub(value);
        return true;
    }

    /**
     * @notice Transfer tokens from the caller
     * @param to    Payee's address
     * @param value Transfer amount
     * @return True if successful
     */
    function transfer(address to, uint256 value)
        external
        override
        whenNotPaused
        notBlacklisted(msg.sender)
        notBlacklisted(to)
        returns (bool)
    {
        _transfer(msg.sender, to, value);
        return true;
    }

    /**
     * @notice Internal function to process transfers
     * @param from  Payer's address
     * @param to    Payee's address
     * @param value Transfer amount
     */
    function _transfer(
        address from,
        address to,
        uint256 value
    ) internal override {
        require(from != address(0), "ERC20: transfer from the zero address");
        require(to != address(0), "ERC20: transfer to the zero address");
        require(
            value <= balances[from],
            "ERC20: transfer amount exceeds balance"
        );

        balances[from] = balances[from].sub(value);
        balances[to] = balances[to].add(value);
        emit Transfer(from, to, value);
    }

    /**
     * @dev Function to add/update a new minter
     * @param minter The address of the minter
     * @param minterAllowedAmount The minting amount allowed for the minter
     * @return True if the operation was successful.
     */
    function configureMinter(address minter, uint256 minterAllowedAmount)
        external
        whenNotPaused
        onlyMasterMinter
        returns (bool)
    {
        minters[minter] = true;
        minterAllowed[minter] = minterAllowedAmount;
        emit MinterConfigured(minter, minterAllowedAmount);
        return true;
    }

    /**
     * @dev Function to remove a minter
     * @param minter The address of the minter to remove
     * @return True if the operation was successful.
     */
    function removeMinter(address minter)
        external
        onlyMasterMinter
        returns (bool)
    {
        minters[minter] = false;
        minterAllowed[minter] = 0;
        emit MinterRemoved(minter);
        return true;
    }

    /**
     * @dev allows a minter to burn some of its own tokens
     * Validates that caller is a minter and that sender is not blacklisted
     * amount is less than or equal to the minter's account balance
     * @param _amount uint256 the amount of tokens to be burned
     */
    function burn(uint256 _amount)
        external
        whenNotPaused
        onlyMinters
        notBlacklisted(msg.sender)
    {
        uint256 balance = balances[msg.sender];
        require(_amount > 0, "FiatToken: burn amount not greater than 0");
        require(balance >= _amount, "FiatToken: burn amount exceeds balance");

        totalSupply_ = totalSupply_.sub(_amount);
        balances[msg.sender] = balance.sub(_amount);
        emit Burn(msg.sender, _amount);
        emit Transfer(msg.sender, address(0), _amount);
    }

    function updateMasterMinter(address _newMasterMinter) external onlyOwner {
        require(
            _newMasterMinter != address(0),
            "FiatToken: new masterMinter is the zero address"
        );
        masterMinter = _newMasterMinter;
        emit MasterMinterChanged(masterMinter);
    }
}

// File: @openzeppelin/contracts/utils/Address.sol

pragma solidity ^0.6.2;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // According to EIP-1052, 0x0 is the value returned for not-yet created accounts
        // and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
        // for accounts without code, i.e. `keccak256('')`
        bytes32 codehash;

            bytes32 accountHash
         = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
        // solhint-disable-next-line no-inline-assembly
        assembly {
            codehash := extcodehash(account)
        }
        return (codehash != accountHash && codehash != 0x0);
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(
            address(this).balance >= amount,
            "Address: insufficient balance"
        );

        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (bool success, ) = recipient.call{ value: amount }("");
        require(
            success,
            "Address: unable to send value, recipient may have reverted"
        );
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain`call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data)
        internal
        returns (bytes memory)
    {
        return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        return _functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value
    ) internal returns (bytes memory) {
        return
            functionCallWithValue(
                target,
                data,
                value,
                "Address: low-level call with value failed"
            );
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(
            address(this).balance >= value,
            "Address: insufficient balance for call"
        );
        return _functionCallWithValue(target, data, value, errorMessage);
    }

    function _functionCallWithValue(
        address target,
        bytes memory data,
        uint256 weiValue,
        string memory errorMessage
    ) private returns (bytes memory) {
        require(isContract(target), "Address: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.call{
            value: weiValue
        }(data);
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// File: @openzeppelin/contracts/token/ERC20/SafeERC20.sol

pragma solidity ^0.6.0;

/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using SafeMath for uint256;
    using Address for address;

    function safeTransfer(
        IERC20 token,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(
            token,
            abi.encodeWithSelector(token.transfer.selector, to, value)
        );
    }

    function safeTransferFrom(
        IERC20 token,
        address from,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(
            token,
            abi.encodeWithSelector(token.transferFrom.selector, from, to, value)
        );
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        // solhint-disable-next-line max-line-length
        require(
            (value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(
            token,
            abi.encodeWithSelector(token.approve.selector, spender, value)
        );
    }

    function safeIncreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        uint256 newAllowance = token.allowance(address(this), spender).add(
            value
        );
        _callOptionalReturn(
            token,
            abi.encodeWithSelector(
                token.approve.selector,
                spender,
                newAllowance
            )
        );
    }

    function safeDecreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        uint256 newAllowance = token.allowance(address(this), spender).sub(
            value,
            "SafeERC20: decreased allowance below zero"
        );
        _callOptionalReturn(
            token,
            abi.encodeWithSelector(
                token.approve.selector,
                spender,
                newAllowance
            )
        );
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(
            data,
            "SafeERC20: low-level call failed"
        );
        if (returndata.length > 0) {
            // Return data is optional
            // solhint-disable-next-line max-line-length
            require(
                abi.decode(returndata, (bool)),
                "SafeERC20: ERC20 operation did not succeed"
            );
        }
    }
}

// File: contracts/v1.1/Rescuable.sol

/**
 * Copyright (c) 2018-2020 CENTRE SECZ
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

pragma solidity 0.6.12;

contract Rescuable is Ownable {
    using SafeERC20 for IERC20;

    address private _rescuer;

    event RescuerChanged(address indexed newRescuer);

    /**
     * @notice Returns current rescuer
     * @return Rescuer's address
     */
    function rescuer() external view returns (address) {
        return _rescuer;
    }

    /**
     * @notice Revert if called by any account other than the rescuer.
     */
    modifier onlyRescuer() {
        require(msg.sender == _rescuer, "Rescuable: caller is not the rescuer");
        _;
    }

    /**
     * @notice Rescue ERC20 tokens locked up in this contract.
     * @param tokenContract ERC20 token contract address
     * @param to        Recipient address
     * @param amount    Amount to withdraw
     */
    function rescueERC20(
        IERC20 tokenContract,
        address to,
        uint256 amount
    ) external onlyRescuer {
        tokenContract.safeTransfer(to, amount);
    }

    /**
     * @notice Assign the rescuer role to a given address.
     * @param newRescuer New rescuer's address
     */
    function updateRescuer(address newRescuer) external onlyOwner {
        require(
            newRescuer != address(0),
            "Rescuable: new rescuer is the zero address"
        );
        _rescuer = newRescuer;
        emit RescuerChanged(newRescuer);
    }
}

// File: contracts/v1.1/FiatTokenV1_1.sol

/**
 * Copyright (c) 2018-2020 CENTRE SECZ
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

pragma solidity 0.6.12;

/**
 * @title FiatTokenV1_1
 * @dev ERC20 Token backed by fiat reserves
 */
contract FiatTokenV1_1 is FiatTokenV1, Rescuable {

}

// File: contracts/v2/AbstractFiatTokenV2.sol

/**
 * Copyright (c) 2018-2020 CENTRE SECZ
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

pragma solidity 0.6.12;

abstract contract AbstractFiatTokenV2 is AbstractFiatTokenV1 {
    function _increaseAllowance(
        address owner,
        address spender,
        uint256 increment
    ) internal virtual;

    function _decreaseAllowance(
        address owner,
        address spender,
        uint256 decrement
    ) internal virtual;
}

// File: contracts/util/ECRecover.sol

/**
 * Copyright (c) 2016-2019 zOS Global Limited
 * Copyright (c) 2018-2020 CENTRE SECZ
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

pragma solidity 0.6.12;

/**
 * @title ECRecover
 * @notice A library that provides a safe ECDSA recovery function
 */
library ECRecover {
    /**
     * @notice Recover signer's address from a signed message
     * @dev Adapted from: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/65e4ffde586ec89af3b7e9140bdc9235d1254853/contracts/cryptography/ECDSA.sol
     * Modifications: Accept v, r, and s as separate arguments
     * @param digest    Keccak-256 hash digest of the signed message
     * @param v         v of the signature
     * @param r         r of the signature
     * @param s         s of the signature
     * @return Signer address
     */
    function recover(
        bytes32 digest,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) internal pure returns (address) {
        // EIP-2 still allows signature malleability for ecrecover(). Remove this possibility and make the signature
        // unique. Appendix F in the Ethereum Yellow paper (https://ethereum.github.io/yellowpaper/paper.pdf), defines
        // the valid range for s in (281): 0 < s < secp256k1n ÷ 2 + 1, and for v in (282): v ∈ {27, 28}. Most
        // signatures from current libraries generate a unique signature with an s-value in the lower half order.
        //
        // If your library generates malleable signatures, such as s-values in the upper range, calculate a new s-value
        // with 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141 - s1 and flip v from 27 to 28 or
        // vice versa. If your library also generates signatures with 0/1 for v instead 27/28, add 27 to v to accept
        // these malleable signatures as well.
        if (
            uint256(s) >
            0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0
        ) {
            revert("ECRecover: invalid signature 's' value");
        }

        if (v != 27 && v != 28) {
            revert("ECRecover: invalid signature 'v' value");
        }

        // If the signature is valid (and not malleable), return the signer address
        address signer = ecrecover(digest, v, r, s);
        require(signer != address(0), "ECRecover: invalid signature");

        return signer;
    }
}

// File: contracts/util/EIP712.sol

/**
 * Copyright (c) 2018-2020 CENTRE SECZ
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

pragma solidity 0.6.12;

/**
 * @title EIP712
 * @notice A library that provides EIP712 helper functions
 */
library EIP712 {
    /**
     * @notice Make EIP712 domain separator
     * @param name      Contract name
     * @param version   Contract version
     * @return Domain separator
     */
    function makeDomainSeparator(string memory name, string memory version)
        internal
        view
        returns (bytes32)
    {
        uint256 chainId;
        assembly {
            chainId := chainid()
        }
        return
            keccak256(
                abi.encode(
                    // keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)")
                    0x8b73c3c69bb8fe3d512ecc4cf759cc79239f7b179b0ffacaa9a75d522b39400f,
                    keccak256(bytes(name)),
                    keccak256(bytes(version)),
                    chainId,
                    address(this)
                )
            );
    }

    /**
     * @notice Recover signer's address from a EIP712 signature
     * @param domainSeparator   Domain separator
     * @param v                 v of the signature
     * @param r                 r of the signature
     * @param s                 s of the signature
     * @param typeHashAndData   Type hash concatenated with data
     * @return Signer's address
     */
    function recover(
        bytes32 domainSeparator,
        uint8 v,
        bytes32 r,
        bytes32 s,
        bytes memory typeHashAndData
    ) internal pure returns (address) {
        bytes32 digest = keccak256(
            abi.encodePacked(
                "\x19\x01",
                domainSeparator,
                keccak256(typeHashAndData)
            )
        );
        return ECRecover.recover(digest, v, r, s);
    }
}

// File: contracts/v2/EIP712Domain.sol

/**
 * Copyright (c) 2018-2020 CENTRE SECZ
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

pragma solidity 0.6.12;

/**
 * @title EIP712 Domain
 */
contract EIP712Domain {
    /**
     * @dev EIP712 Domain Separator
     */
    bytes32 public DOMAIN_SEPARATOR;
}

// File: contracts/v2/EIP3009.sol

/**
 * Copyright (c) 2018-2020 CENTRE SECZ
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

pragma solidity 0.6.12;

/**
 * @title EIP-3009
 * @notice Provide internal implementation for gas-abstracted transfers
 * @dev Contracts that inherit from this must wrap these with publicly
 * accessible functions, optionally adding modifiers where necessary
 */
abstract contract EIP3009 is AbstractFiatTokenV2, EIP712Domain {
    // keccak256("TransferWithAuthorization(address from,address to,uint256 value,uint256 validAfter,uint256 validBefore,bytes32 nonce)")
    bytes32
        public constant TRANSFER_WITH_AUTHORIZATION_TYPEHASH = 0x7c7c6cdb67a18743f49ec6fa9b35f50d52ed05cbed4cc592e13b44501c1a2267;

    // keccak256("ReceiveWithAuthorization(address from,address to,uint256 value,uint256 validAfter,uint256 validBefore,bytes32 nonce)")
    bytes32
        public constant RECEIVE_WITH_AUTHORIZATION_TYPEHASH = 0xd099cc98ef71107a616c4f0f941f04c322d8e254fe26b3c6668db87aae413de8;

    // keccak256("CancelAuthorization(address authorizer,bytes32 nonce)")
    bytes32
        public constant CANCEL_AUTHORIZATION_TYPEHASH = 0x158b0a9edf7a828aad02f63cd515c68ef2f50ba807396f6d12842833a1597429;

    /**
     * @dev authorizer address => nonce => bool (true if nonce is used)
     */
    mapping(address => mapping(bytes32 => bool)) private _authorizationStates;

    event AuthorizationUsed(address indexed authorizer, bytes32 indexed nonce);
    event AuthorizationCanceled(
        address indexed authorizer,
        bytes32 indexed nonce
    );

    /**
     * @notice Returns the state of an authorization
     * @dev Nonces are randomly generated 32-byte data unique to the
     * authorizer's address
     * @param authorizer    Authorizer's address
     * @param nonce         Nonce of the authorization
     * @return True if the nonce is used
     */
    function authorizationState(address authorizer, bytes32 nonce)
        external
        view
        returns (bool)
    {
        return _authorizationStates[authorizer][nonce];
    }

    /**
     * @notice Execute a transfer with a signed authorization
     * @param from          Payer's address (Authorizer)
     * @param to            Payee's address
     * @param value         Amount to be transferred
     * @param validAfter    The time after which this is valid (unix time)
     * @param validBefore   The time before which this is valid (unix time)
     * @param nonce         Unique nonce
     * @param v             v of the signature
     * @param r             r of the signature
     * @param s             s of the signature
     */
    function _transferWithAuthorization(
        address from,
        address to,
        uint256 value,
        uint256 validAfter,
        uint256 validBefore,
        bytes32 nonce,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) internal {
        _requireValidAuthorization(from, nonce, validAfter, validBefore);

        bytes memory data = abi.encode(
            TRANSFER_WITH_AUTHORIZATION_TYPEHASH,
            from,
            to,
            value,
            validAfter,
            validBefore,
            nonce
        );
        require(
            EIP712.recover(DOMAIN_SEPARATOR, v, r, s, data) == from,
            "FiatTokenV2: invalid signature"
        );

        _markAuthorizationAsUsed(from, nonce);
        _transfer(from, to, value);
    }

    /**
     * @notice Receive a transfer with a signed authorization from the payer
     * @dev This has an additional check to ensure that the payee's address
     * matches the caller of this function to prevent front-running attacks.
     * @param from          Payer's address (Authorizer)
     * @param to            Payee's address
     * @param value         Amount to be transferred
     * @param validAfter    The time after which this is valid (unix time)
     * @param validBefore   The time before which this is valid (unix time)
     * @param nonce         Unique nonce
     * @param v             v of the signature
     * @param r             r of the signature
     * @param s             s of the signature
     */
    function _receiveWithAuthorization(
        address from,
        address to,
        uint256 value,
        uint256 validAfter,
        uint256 validBefore,
        bytes32 nonce,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) internal {
        require(to == msg.sender, "FiatTokenV2: caller must be the payee");
        _requireValidAuthorization(from, nonce, validAfter, validBefore);

        bytes memory data = abi.encode(
            RECEIVE_WITH_AUTHORIZATION_TYPEHASH,
            from,
            to,
            value,
            validAfter,
            validBefore,
            nonce
        );
        require(
            EIP712.recover(DOMAIN_SEPARATOR, v, r, s, data) == from,
            "FiatTokenV2: invalid signature"
        );

        _markAuthorizationAsUsed(from, nonce);
        _transfer(from, to, value);
    }

    /**
     * @notice Attempt to cancel an authorization
     * @param authorizer    Authorizer's address
     * @param nonce         Nonce of the authorization
     * @param v             v of the signature
     * @param r             r of the signature
     * @param s             s of the signature
     */
    function _cancelAuthorization(
        address authorizer,
        bytes32 nonce,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) internal {
        _requireUnusedAuthorization(authorizer, nonce);

        bytes memory data = abi.encode(
            CANCEL_AUTHORIZATION_TYPEHASH,
            authorizer,
            nonce
        );
        require(
            EIP712.recover(DOMAIN_SEPARATOR, v, r, s, data) == authorizer,
            "FiatTokenV2: invalid signature"
        );

        _authorizationStates[authorizer][nonce] = true;
        emit AuthorizationCanceled(authorizer, nonce);
    }

    /**
     * @notice Check that an authorization is unused
     * @param authorizer    Authorizer's address
     * @param nonce         Nonce of the authorization
     */
    function _requireUnusedAuthorization(address authorizer, bytes32 nonce)
        private
        view
    {
        require(
            !_authorizationStates[authorizer][nonce],
            "FiatTokenV2: authorization is used or canceled"
        );
    }

    /**
     * @notice Check that authorization is valid
     * @param authorizer    Authorizer's address
     * @param nonce         Nonce of the authorization
     * @param validAfter    The time after which this is valid (unix time)
     * @param validBefore   The time before which this is valid (unix time)
     */
    function _requireValidAuthorization(
        address authorizer,
        bytes32 nonce,
        uint256 validAfter,
        uint256 validBefore
    ) private view {
        require(
            now > validAfter,
            "FiatTokenV2: authorization is not yet valid"
        );
        require(now < validBefore, "FiatTokenV2: authorization is expired");
        _requireUnusedAuthorization(authorizer, nonce);
    }

    /**
     * @notice Mark an authorization as used
     * @param authorizer    Authorizer's address
     * @param nonce         Nonce of the authorization
     */
    function _markAuthorizationAsUsed(address authorizer, bytes32 nonce)
        private
    {
        _authorizationStates[authorizer][nonce] = true;
        emit AuthorizationUsed(authorizer, nonce);
    }
}

// File: contracts/v2/EIP2612.sol

/**
 * Copyright (c) 2018-2020 CENTRE SECZ
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

pragma solidity 0.6.12;

/**
 * @title EIP-2612
 * @notice Provide internal implementation for gas-abstracted approvals
 */
abstract contract EIP2612 is AbstractFiatTokenV2, EIP712Domain {
    // keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)")
    bytes32
        public constant PERMIT_TYPEHASH = 0x6e71edae12b1b97f4d1f60370fef10105fa2faae0126114a169c64845d6126c9;

    mapping(address => uint256) private _permitNonces;

    /**
     * @notice Nonces for permit
     * @param owner Token owner's address (Authorizer)
     * @return Next nonce
     */
    function nonces(address owner) external view returns (uint256) {
        return _permitNonces[owner];
    }

    /**
     * @notice Verify a signed approval permit and execute if valid
     * @param owner     Token owner's address (Authorizer)
     * @param spender   Spender's address
     * @param value     Amount of allowance
     * @param deadline  The time at which this expires (unix time)
     * @param v         v of the signature
     * @param r         r of the signature
     * @param s         s of the signature
     */
    function _permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) internal {
        require(deadline >= now, "FiatTokenV2: permit is expired");

        bytes memory data = abi.encode(
            PERMIT_TYPEHASH,
            owner,
            spender,
            value,
            _permitNonces[owner]++,
            deadline
        );
        require(
            EIP712.recover(DOMAIN_SEPARATOR, v, r, s, data) == owner,
            "EIP2612: invalid signature"
        );

        _approve(owner, spender, value);
    }
}

// File: contracts/v2/FiatTokenV2.sol

/**
 * Copyright (c) 2018-2020 CENTRE SECZ
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

pragma solidity 0.6.12;

/**
 * @title FiatToken V2
 * @notice ERC20 Token backed by fiat reserves, version 2
 */
contract FiatTokenV2 is FiatTokenV1_1, EIP3009, EIP2612 {
    uint8 internal _initializedVersion;

    /**
     * @notice Initialize v2
     * @param newName   New token name
     */
    function initializeV2(string calldata newName) external {
        // solhint-disable-next-line reason-string
        require(initialized && _initializedVersion == 0);
        name = newName;
        DOMAIN_SEPARATOR = EIP712.makeDomainSeparator(newName, "2");
        _initializedVersion = 1;
    }

    /**
     * @notice Increase the allowance by a given increment
     * @param spender   Spender's address
     * @param increment Amount of increase in allowance
     * @return True if successful
     */
    function increaseAllowance(address spender, uint256 increment)
        external
        whenNotPaused
        notBlacklisted(msg.sender)
        notBlacklisted(spender)
        returns (bool)
    {
        _increaseAllowance(msg.sender, spender, increment);
        return true;
    }

    /**
     * @notice Decrease the allowance by a given decrement
     * @param spender   Spender's address
     * @param decrement Amount of decrease in allowance
     * @return True if successful
     */
    function decreaseAllowance(address spender, uint256 decrement)
        external
        whenNotPaused
        notBlacklisted(msg.sender)
        notBlacklisted(spender)
        returns (bool)
    {
        _decreaseAllowance(msg.sender, spender, decrement);
        return true;
    }

    /**
     * @notice Execute a transfer with a signed authorization
     * @param from          Payer's address (Authorizer)
     * @param to            Payee's address
     * @param value         Amount to be transferred
     * @param validAfter    The time after which this is valid (unix time)
     * @param validBefore   The time before which this is valid (unix time)
     * @param nonce         Unique nonce
     * @param v             v of the signature
     * @param r             r of the signature
     * @param s             s of the signature
     */
    function transferWithAuthorization(
        address from,
        address to,
        uint256 value,
        uint256 validAfter,
        uint256 validBefore,
        bytes32 nonce,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external whenNotPaused notBlacklisted(from) notBlacklisted(to) {
        _transferWithAuthorization(
            from,
            to,
            value,
            validAfter,
            validBefore,
            nonce,
            v,
            r,
            s
        );
    }

    /**
     * @notice Receive a transfer with a signed authorization from the payer
     * @dev This has an additional check to ensure that the payee's address
     * matches the caller of this function to prevent front-running attacks.
     * @param from          Payer's address (Authorizer)
     * @param to            Payee's address
     * @param value         Amount to be transferred
     * @param validAfter    The time after which this is valid (unix time)
     * @param validBefore   The time before which this is valid (unix time)
     * @param nonce         Unique nonce
     * @param v             v of the signature
     * @param r             r of the signature
     * @param s             s of the signature
     */
    function receiveWithAuthorization(
        address from,
        address to,
        uint256 value,
        uint256 validAfter,
        uint256 validBefore,
        bytes32 nonce,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external whenNotPaused notBlacklisted(from) notBlacklisted(to) {
        _receiveWithAuthorization(
            from,
            to,
            value,
            validAfter,
            validBefore,
            nonce,
            v,
            r,
            s
        );
    }

    /**
     * @notice Attempt to cancel an authorization
     * @dev Works only if the authorization is not yet used.
     * @param authorizer    Authorizer's address
     * @param nonce         Nonce of the authorization
     * @param v             v of the signature
     * @param r             r of the signature
     * @param s             s of the signature
     */
    function cancelAuthorization(
        address authorizer,
        bytes32 nonce,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external whenNotPaused {
        _cancelAuthorization(authorizer, nonce, v, r, s);
    }

    /**
     * @notice Update allowance with a signed permit
     * @param owner       Token owner's address (Authorizer)
     * @param spender     Spender's address
     * @param value       Amount of allowance
     * @param deadline    Expiration time, seconds since the epoch
     * @param v           v of the signature
     * @param r           r of the signature
     * @param s           s of the signature
     */
    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external whenNotPaused notBlacklisted(owner) notBlacklisted(spender) {
        _permit(owner, spender, value, deadline, v, r, s);
    }

    /**
     * @notice Internal function to increase the allowance by a given increment
     * @param owner     Token owner's address
     * @param spender   Spender's address
     * @param increment Amount of increase
     */
    function _increaseAllowance(
        address owner,
        address spender,
        uint256 increment
    ) internal override {
        _approve(owner, spender, allowed[owner][spender].add(increment));
    }

    /**
     * @notice Internal function to decrease the allowance by a given decrement
     * @param owner     Token owner's address
     * @param spender   Spender's address
     * @param decrement Amount of decrease
     */
    function _decreaseAllowance(
        address owner,
        address spender,
        uint256 decrement
    ) internal override {
        _approve(
            owner,
            spender,
            allowed[owner][spender].sub(
                decrement,
                "ERC20: decreased allowance below zero"
            )
        );
    }
}

// File: contracts/v2/FiatTokenV2_1.sol

/**
 * Copyright (c) 2018-2020 CENTRE SECZ
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

pragma solidity 0.6.12;

// solhint-disable func-name-mixedcase

/**
 * @title FiatToken V2.1
 * @notice ERC20 Token backed by fiat reserves, version 2.1
 */
contract FiatTokenV2_1 is FiatTokenV2 {
    /**
     * @notice Initialize v2.1
     * @param lostAndFound  The address to which the locked funds are sent
     */
    function initializeV2_1(address lostAndFound) external {
        // solhint-disable-next-line reason-string
        require(_initializedVersion == 1);

        uint256 lockedAmount = balances[address(this)];
        if (lockedAmount > 0) {
            _transfer(address(this), lostAndFound, lockedAmount);
        }
        blacklisted[address(this)] = true;

        _initializedVersion = 2;
    }

    /**
     * @notice Version string for the EIP712 domain separator
     * @return Version string
     */
    function version() external view returns (string memory) {
        return "2";
    }
}

# @version 0.2.8
"""
@title Curve aPool
@author Curve.Fi
@license Copyright (c) Curve.Fi, 2020 - all rights reserved
@notice Pool implementation with aToken-style lending
"""

from vyper.interfaces import ERC20


interface LendingPool:
    def withdraw(_underlying_asset: address, _amount: uint256, _receiver: address): nonpayable

interface CurveToken:
    def mint(_to: address, _value: uint256) -> bool: nonpayable
    def burnFrom(_to: address, _value: uint256) -> bool: nonpayable


# Events
event TokenExchange:
    buyer: indexed(address)
    sold_id: int128
    tokens_sold: uint256
    bought_id: int128
    tokens_bought: uint256

event TokenExchangeUnderlying:
    buyer: indexed(address)
    sold_id: int128
    tokens_sold: uint256
    bought_id: int128
    tokens_bought: uint256

event AddLiquidity:
    provider: indexed(address)
    token_amounts: uint256[N_COINS]
    fees: uint256[N_COINS]
    invariant: uint256
    token_supply: uint256

event RemoveLiquidity:
    provider: indexed(address)
    token_amounts: uint256[N_COINS]
    fees: uint256[N_COINS]
    token_supply: uint256

event RemoveLiquidityOne:
    provider: indexed(address)
    token_amount: uint256
    coin_amount: uint256

event RemoveLiquidityImbalance:
    provider: indexed(address)
    token_amounts: uint256[N_COINS]
    fees: uint256[N_COINS]
    invariant: uint256
    token_supply: uint256

event CommitNewAdmin:
    deadline: indexed(uint256)
    admin: indexed(address)

event NewAdmin:
    admin: indexed(address)

event CommitNewFee:
    deadline: indexed(uint256)
    fee: uint256
    admin_fee: uint256
    offpeg_fee_multiplier: uint256

event NewFee:
    fee: uint256
    admin_fee: uint256
    offpeg_fee_multiplier: uint256

event RampA:
    old_A: uint256
    new_A: uint256
    initial_time: uint256
    future_time: uint256

event StopRampA:
    A: uint256
    t: uint256


# These constants must be set prior to compiling
N_COINS: constant(int128) = 3
PRECISION_MUL: constant(uint256[N_COINS]) = [1, 1000000000000, 1000000000000]

# fixed constants
FEE_DENOMINATOR: constant(uint256) = 10 ** 10
PRECISION: constant(uint256) = 10 ** 18  # The precision to convert to

MAX_ADMIN_FEE: constant(uint256) = 10 * 10 ** 9
MAX_FEE: constant(uint256) = 5 * 10 ** 9

MAX_A: constant(uint256) = 10 ** 6
MAX_A_CHANGE: constant(uint256) = 10
A_PRECISION: constant(uint256) = 100

ADMIN_ACTIONS_DELAY: constant(uint256) = 3 * 86400
MIN_RAMP_TIME: constant(uint256) = 86400

coins: public(address[N_COINS])
underlying_coins: public(address[N_COINS])
admin_balances: public(uint256[N_COINS])

fee: public(uint256)  # fee * 1e10
offpeg_fee_multiplier: public(uint256)  # * 1e10
admin_fee: public(uint256)  # admin_fee * 1e10

owner: public(address)
lp_token: public(address)

aave_lending_pool: address
aave_referral: uint256

initial_A: public(uint256)
future_A: public(uint256)
initial_A_time: public(uint256)
future_A_time: public(uint256)

admin_actions_deadline: public(uint256)
transfer_ownership_deadline: public(uint256)
future_fee: public(uint256)
future_admin_fee: public(uint256)
future_offpeg_fee_multiplier: public(uint256)  # * 1e10
future_owner: public(address)

is_killed: bool
kill_deadline: uint256
KILL_DEADLINE_DT: constant(uint256) = 2 * 30 * 86400


@external
def __init__(
    _coins: address[N_COINS],
    _underlying_coins: address[N_COINS],
    _pool_token: address,
    _aave_lending_pool: address,
    _A: uint256,
    _fee: uint256,
    _admin_fee: uint256,
    _offpeg_fee_multiplier: uint256,
):
    """
    @notice Contract constructor
    @param _coins List of wrapped coin addresses
    @param _underlying_coins List of underlying coin addresses
    @param _pool_token Pool LP token address
    @param _aave_lending_pool Aave lending pool address
    @param _A Amplification coefficient multiplied by n * (n - 1)
    @param _fee Swap fee expressed as an integer with 1e10 precision
    @param _admin_fee Percentage of fee taken as an admin fee,
                      expressed as an integer with 1e10 precision
    @param _offpeg_fee_multiplier Offpeg fee multiplier
    """
    for i in range(N_COINS):
        assert _coins[i] != ZERO_ADDRESS
        assert _underlying_coins[i] != ZERO_ADDRESS

    self.coins = _coins
    self.underlying_coins = _underlying_coins
    self.initial_A = _A * A_PRECISION
    self.future_A = _A * A_PRECISION
    self.fee = _fee
    self.admin_fee = _admin_fee
    self.offpeg_fee_multiplier = _offpeg_fee_multiplier
    self.owner = msg.sender
    self.kill_deadline = block.timestamp + KILL_DEADLINE_DT
    self.lp_token = _pool_token
    self.aave_lending_pool = _aave_lending_pool

    # approve transfer of underlying coin to aave lending pool
    for coin in _underlying_coins:
        _response: Bytes[32] = raw_call(
            coin,
            concat(
                method_id("approve(address,uint256)"),
                convert(_aave_lending_pool, bytes32),
                convert(MAX_UINT256, bytes32)
            ),
            max_outsize=32
        )
        if len(_response) != 0:
            assert convert(_response, bool)



@view
@internal
def _A() -> uint256:
    t1: uint256 = self.future_A_time
    A1: uint256 = self.future_A

    if block.timestamp < t1:
        # handle ramping up and down of A
        A0: uint256 = self.initial_A
        t0: uint256 = self.initial_A_time
        # Expressions in uint256 cannot have negative numbers, thus "if"
        if A1 > A0:
            return A0 + (A1 - A0) * (block.timestamp - t0) / (t1 - t0)
        else:
            return A0 - (A0 - A1) * (block.timestamp - t0) / (t1 - t0)

    else:  # when t1 == 0 or block.timestamp >= t1
        return A1


@view
@external
def A() -> uint256:
    return self._A() / A_PRECISION


@view
@external
def A_precise() -> uint256:
    return self._A()


@pure
@internal
def _dynamic_fee(xpi: uint256, xpj: uint256, _fee: uint256, _feemul: uint256) -> uint256:
    if _feemul <= FEE_DENOMINATOR:
        return _fee
    else:
        xps2: uint256 = (xpi + xpj)
        xps2 *= xps2  # Doing just ** 2 can overflow apparently
        return (_feemul * _fee) / (
            (_feemul - FEE_DENOMINATOR) * 4 * xpi * xpj / xps2 + \
            FEE_DENOMINATOR)


@view
@external
def dynamic_fee(i: int128, j: int128) -> uint256:
    """
    @notice Return the fee for swapping between `i` and `j`
    @param i Index value for the coin to send
    @param j Index value of the coin to recieve
    @return Swap fee expressed as an integer with 1e10 precision
    """
    precisions: uint256[N_COINS] = PRECISION_MUL
    xpi: uint256 = (ERC20(self.coins[i]).balanceOf(self) - self.admin_balances[i]) * precisions[i]
    xpj: uint256 = (ERC20(self.coins[j]).balanceOf(self) - self.admin_balances[j]) * precisions[j]
    return self._dynamic_fee(xpi, xpj, self.fee, self.offpeg_fee_multiplier)


@view
@external
def balances(i: uint256) -> uint256:
    """
    @notice Get the current balance of a coin within the
            pool, less the accrued admin fees
    @param i Index value for the coin to query balance of
    @return Token balance
    """
    return ERC20(self.coins[i]).balanceOf(self) - self.admin_balances[i]


@view
@internal
def _balances() -> uint256[N_COINS]:
    result: uint256[N_COINS] = empty(uint256[N_COINS])
    for i in range(N_COINS):
        result[i] = ERC20(self.coins[i]).balanceOf(self) - self.admin_balances[i]
    return result


@pure
@internal
def get_D(xp: uint256[N_COINS], amp: uint256) -> uint256:
    """
    D invariant calculation in non-overflowing integer operations
    iteratively

    A * sum(x_i) * n**n + D = A * D * n**n + D**(n+1) / (n**n * prod(x_i))

    Converging solution:
    D[j+1] = (A * n**n * sum(x_i) - D[j]**(n+1) / (n**n prod(x_i))) / (A * n**n - 1)
    """
    S: uint256 = 0

    for _x in xp:
        S += _x
    if S == 0:
        return 0

    Dprev: uint256 = 0
    D: uint256 = S
    Ann: uint256 = amp * N_COINS
    for _i in range(255):
        D_P: uint256 = D
        for _x in xp:
            D_P = D_P * D / (_x * N_COINS + 1)  # +1 is to prevent /0
        Dprev = D
        D = (Ann * S / A_PRECISION + D_P * N_COINS) * D / ((Ann - A_PRECISION) * D / A_PRECISION + (N_COINS + 1) * D_P)
        # Equality with the precision of 1
        if D > Dprev:
            if D - Dprev <= 1:
                return D
        else:
            if Dprev - D <= 1:
                return D
    # convergence typically occurs in 4 rounds or less, this should be unreachable!
    # if it does happen the pool is borked and LPs can withdraw via `remove_liquidity`
    raise



@view
@internal
def get_D_precisions(coin_balances: uint256[N_COINS], amp: uint256) -> uint256:
    xp: uint256[N_COINS] = PRECISION_MUL
    for i in range(N_COINS):
        xp[i] *= coin_balances[i]
    return self.get_D(xp, amp)


@view
@external
def get_virtual_price() -> uint256:
    """
    @notice The current virtual price of the pool LP token
    @dev Useful for calculating profits
    @return LP token virtual price normalized to 1e18
    """
    D: uint256 = self.get_D_precisions(self._balances(), self._A())
    # D is in the units similar to DAI (e.g. converted to precision 1e18)
    # When balanced, D = n * x_u - total virtual value of the portfolio
    token_supply: uint256 = ERC20(self.lp_token).totalSupply()
    return D * PRECISION / token_supply


@view
@external
def calc_token_amount(_amounts: uint256[N_COINS], is_deposit: bool) -> uint256:
    """
    @notice Calculate addition or reduction in token supply from a deposit or withdrawal
    @dev This calculation accounts for slippage, but not fees.
         Needed to prevent front-running, not for precise calculations!
    @param _amounts Amount of each coin being deposited
    @param is_deposit set True for deposits, False for withdrawals
    @return Expected amount of LP tokens received
    """
    coin_balances: uint256[N_COINS] = self._balances()
    amp: uint256 = self._A()
    D0: uint256 = self.get_D_precisions(coin_balances, amp)
    for i in range(N_COINS):
        if is_deposit:
            coin_balances[i] += _amounts[i]
        else:
            coin_balances[i] -= _amounts[i]
    D1: uint256 = self.get_D_precisions(coin_balances, amp)
    token_amount: uint256 = ERC20(self.lp_token).totalSupply()
    diff: uint256 = 0
    if is_deposit:
        diff = D1 - D0
    else:
        diff = D0 - D1
    return diff * token_amount / D0


@external
@nonreentrant('lock')
def add_liquidity(_amounts: uint256[N_COINS], _min_mint_amount: uint256, _use_underlying: bool = False) -> uint256:
    """
    @notice Deposit coins into the pool
    @param _amounts List of amounts of coins to deposit
    @param _min_mint_amount Minimum amount of LP tokens to mint from the deposit
    @param _use_underlying If True, deposit underlying assets instead of aTokens
    @return Amount of LP tokens received by depositing
    """

    assert not self.is_killed  # dev: is killed

    # Initial invariant
    amp: uint256 = self._A()
    old_balances: uint256[N_COINS] = self._balances()
    lp_token: address = self.lp_token
    token_supply: uint256 = ERC20(lp_token).totalSupply()
    D0: uint256 = 0
    if token_supply != 0:
        D0 = self.get_D_precisions(old_balances, amp)

    new_balances: uint256[N_COINS] = old_balances
    for i in range(N_COINS):
        if token_supply == 0:
            assert _amounts[i] != 0  # dev: initial deposit requires all coins
        new_balances[i] += _amounts[i]

    # Invariant after change
    D1: uint256 = self.get_D_precisions(new_balances, amp)
    assert D1 > D0

    # We need to recalculate the invariant accounting for fees
    # to calculate fair user's share
    fees: uint256[N_COINS] = empty(uint256[N_COINS])
    mint_amount: uint256 = 0
    if token_supply != 0:
        # Only account for fees if we are not the first to deposit
        ys: uint256 = (D0 + D1) / N_COINS
        _fee: uint256 = self.fee * N_COINS / (4 * (N_COINS - 1))
        _feemul: uint256 = self.offpeg_fee_multiplier
        _admin_fee: uint256 = self.admin_fee
        difference: uint256 = 0
        for i in range(N_COINS):
            ideal_balance: uint256 = D1 * old_balances[i] / D0
            new_balance: uint256 = new_balances[i]
            if ideal_balance > new_balance:
                difference = ideal_balance - new_balance
            else:
                difference = new_balance - ideal_balance
            xs: uint256 = old_balances[i] + new_balance
            fees[i] = self._dynamic_fee(xs, ys, _fee, _feemul) * difference / FEE_DENOMINATOR
            if _admin_fee != 0:
                self.admin_balances[i] += fees[i] * _admin_fee / FEE_DENOMINATOR
            new_balances[i] = new_balance - fees[i]
        D2: uint256 = self.get_D_precisions(new_balances, amp)
        mint_amount = token_supply * (D2 - D0) / D0
    else:
        mint_amount = D1  # Take the dust if there was any

    assert mint_amount >= _min_mint_amount, "Slippage screwed you"

    # Take coins from the sender
    if _use_underlying:
        lending_pool: address = self.aave_lending_pool
        aave_referral: bytes32 = convert(self.aave_referral, bytes32)

        # Take coins from the sender
        for i in range(N_COINS):
            amount: uint256 = _amounts[i]
            if amount != 0:
                coin: address = self.underlying_coins[i]
                # transfer underlying coin from msg.sender to self
                _response: Bytes[32] = raw_call(
                    coin,
                    concat(
                        method_id("transferFrom(address,address,uint256)"),
                        convert(msg.sender, bytes32),
                        convert(self, bytes32),
                        convert(amount, bytes32)
                    ),
                    max_outsize=32
                )
                if len(_response) != 0:
                    assert convert(_response, bool)

                # deposit to aave lending pool
                raw_call(
                    lending_pool,
                    concat(
                        method_id("deposit(address,uint256,address,uint16)"),
                        convert(coin, bytes32),
                        convert(amount, bytes32),
                        convert(self, bytes32),
                        aave_referral,
                    )
                )
    else:
        for i in range(N_COINS):
            amount: uint256 = _amounts[i]
            if amount != 0:
                assert ERC20(self.coins[i]).transferFrom(msg.sender, self, amount) # dev: failed transfer

    # Mint pool tokens
    CurveToken(lp_token).mint(msg.sender, mint_amount)

    log AddLiquidity(msg.sender, _amounts, fees, D1, token_supply + mint_amount)

    return mint_amount


@view
@internal
def get_y(i: int128, j: int128, x: uint256, xp: uint256[N_COINS]) -> uint256:
    """
    Calculate x[j] if one makes x[i] = x

    Done by solving quadratic equation iteratively.
    x_1**2 + x1 * (sum' - (A*n**n - 1) * D / (A * n**n)) = D ** (n + 1) / (n ** (2 * n) * prod' * A)
    x_1**2 + b*x_1 = c

    x_1 = (x_1**2 + c) / (2*x_1 + b)
    """
    # x in the input is converted to the same price/precision

    assert i != j       # dev: same coin
    assert j >= 0       # dev: j below zero
    assert j < N_COINS  # dev: j above N_COINS

    # should be unreachable, but good for safety
    assert i >= 0
    assert i < N_COINS

    amp: uint256 = self._A()
    D: uint256 = self.get_D(xp, amp)
    Ann: uint256 = amp * N_COINS
    c: uint256 = D
    S_: uint256 = 0
    _x: uint256 = 0
    y_prev: uint256 = 0

    for _i in range(N_COINS):
        if _i == i:
            _x = x
        elif _i != j:
            _x = xp[_i]
        else:
            continue
        S_ += _x
        c = c * D / (_x * N_COINS)
    c = c * D * A_PRECISION / (Ann * N_COINS)
    b: uint256 = S_ + D * A_PRECISION / Ann  # - D
    y: uint256 = D
    for _i in range(255):
        y_prev = y
        y = (y*y + c) / (2 * y + b - D)
        # Equality with the precision of 1
        if y > y_prev:
            if y - y_prev <= 1:
                return y
        else:
            if y_prev - y <= 1:
                return y
    raise


@view
@internal
def _get_dy(i: int128, j: int128, dx: uint256) -> uint256:
    xp: uint256[N_COINS] = self._balances()
    precisions: uint256[N_COINS] = PRECISION_MUL
    for k in range(N_COINS):
        xp[k] *= precisions[k]

    x: uint256 = xp[i] + dx * precisions[i]
    y: uint256 = self.get_y(i, j, x, xp)
    dy: uint256 = (xp[j] - y) / precisions[j]
    _fee: uint256 = self._dynamic_fee(
            (xp[i] + x) / 2, (xp[j] + y) / 2, self.fee, self.offpeg_fee_multiplier
        ) * dy / FEE_DENOMINATOR
    return dy - _fee


@view
@external
def get_dy(i: int128, j: int128, dx: uint256) -> uint256:
    return self._get_dy(i, j, dx)


@view
@external
def get_dy_underlying(i: int128, j: int128, dx: uint256) -> uint256:
    return self._get_dy(i, j, dx)


@internal
def _exchange(i: int128, j: int128, dx: uint256) -> uint256:
    assert not self.is_killed  # dev: is killed
    # dx and dy are in aTokens

    xp: uint256[N_COINS] = self._balances()
    precisions: uint256[N_COINS] = PRECISION_MUL
    for k in range(N_COINS):
        xp[k] *= precisions[k]

    x: uint256 = xp[i] + dx * precisions[i]
    y: uint256 = self.get_y(i, j, x, xp)
    dy: uint256 = xp[j] - y
    dy_fee: uint256 = dy * self._dynamic_fee(
            (xp[i] + x) / 2, (xp[j] + y) / 2, self.fee, self.offpeg_fee_multiplier
        ) / FEE_DENOMINATOR

    admin_fee: uint256 = self.admin_fee
    if admin_fee != 0:
        dy_admin_fee: uint256 = dy_fee * admin_fee / FEE_DENOMINATOR
        if dy_admin_fee != 0:
            self.admin_balances[j] += dy_admin_fee / precisions[j]

    return (dy - dy_fee) / precisions[j]


@external
@nonreentrant('lock')
def exchange(i: int128, j: int128, dx: uint256, min_dy: uint256) -> uint256:
    """
    @notice Perform an exchange between two coins
    @dev Index values can be found via the `coins` public getter method
    @param i Index value for the coin to send
    @param j Index valie of the coin to recieve
    @param dx Amount of `i` being exchanged
    @param min_dy Minimum amount of `j` to receive
    @return Actual amount of `j` received
    """
    dy: uint256 = self._exchange(i, j, dx)
    assert dy >= min_dy, "Exchange resulted in fewer coins than expected"

    assert ERC20(self.coins[i]).transferFrom(msg.sender, self, dx)
    assert ERC20(self.coins[j]).transfer(msg.sender, dy)

    log TokenExchange(msg.sender, i, dx, j, dy)

    return dy


@external
@nonreentrant('lock')
def exchange_underlying(i: int128, j: int128, dx: uint256, min_dy: uint256) -> uint256:
    """
    @notice Perform an exchange between two underlying coins
    @dev Index values can be found via the `underlying_coins` public getter method
    @param i Index value for the underlying coin to send
    @param j Index valie of the underlying coin to recieve
    @param dx Amount of `i` being exchanged
    @param min_dy Minimum amount of `j` to receive
    @return Actual amount of `j` received
    """
    dy: uint256 = self._exchange(i, j, dx)
    assert dy >= min_dy, "Exchange resulted in fewer coins than expected"

    u_coin_i: address = self.underlying_coins[i]
    lending_pool: address = self.aave_lending_pool

    # transfer underlying coin from msg.sender to self
    _response: Bytes[32] = raw_call(
        u_coin_i,
        concat(
            method_id("transferFrom(address,address,uint256)"),
            convert(msg.sender, bytes32),
            convert(self, bytes32),
            convert(dx, bytes32)
        ),
        max_outsize=32
    )
    if len(_response) != 0:
        assert convert(_response, bool)

    # deposit to aave lending pool
    raw_call(
        lending_pool,
        concat(
            method_id("deposit(address,uint256,address,uint16)"),
            convert(u_coin_i, bytes32),
            convert(dx, bytes32),
            convert(self, bytes32),
            convert(self.aave_referral, bytes32),
        )
    )
    # withdraw `j` underlying from lending pool and transfer to caller
    LendingPool(lending_pool).withdraw(self.underlying_coins[j], dy, msg.sender)

    log TokenExchangeUnderlying(msg.sender, i, dx, j, dy)

    return dy


@external
@nonreentrant('lock')
def remove_liquidity(
    _amount: uint256,
    _min_amounts: uint256[N_COINS],
    _use_underlying: bool = False,
) -> uint256[N_COINS]:
    """
    @notice Withdraw coins from the pool
    @dev Withdrawal amounts are based on current deposit ratios
    @param _amount Quantity of LP tokens to burn in the withdrawal
    @param _min_amounts Minimum amounts of underlying coins to receive
    @param _use_underlying If True, withdraw underlying assets instead of aTokens
    @return List of amounts of coins that were withdrawn
    """
    amounts: uint256[N_COINS] = self._balances()
    lp_token: address = self.lp_token
    total_supply: uint256 = ERC20(lp_token).totalSupply()
    CurveToken(lp_token).burnFrom(msg.sender, _amount)  # dev: insufficient funds

    lending_pool: address = ZERO_ADDRESS
    if _use_underlying:
        lending_pool = self.aave_lending_pool

    for i in range(N_COINS):
        value: uint256 = amounts[i] * _amount / total_supply
        assert value >= _min_amounts[i], "Withdrawal resulted in fewer coins than expected"
        amounts[i] = value
        if _use_underlying:
            LendingPool(lending_pool).withdraw(self.underlying_coins[i], value, msg.sender)
        else:
            assert ERC20(self.coins[i]).transfer(msg.sender, value)

    log RemoveLiquidity(msg.sender, amounts, empty(uint256[N_COINS]), total_supply - _amount)

    return amounts


@external
@nonreentrant('lock')
def remove_liquidity_imbalance(
    _amounts: uint256[N_COINS],
    _max_burn_amount: uint256,
    _use_underlying: bool = False
) -> uint256:
    """
    @notice Withdraw coins from the pool in an imbalanced amount
    @param _amounts List of amounts of underlying coins to withdraw
    @param _max_burn_amount Maximum amount of LP token to burn in the withdrawal
    @param _use_underlying If True, withdraw underlying assets instead of aTokens
    @return Actual amount of the LP token burned in the withdrawal
    """
    assert not self.is_killed  # dev: is killed

    amp: uint256 = self._A()
    old_balances: uint256[N_COINS] = self._balances()
    D0: uint256 = self.get_D_precisions(old_balances, amp)
    new_balances: uint256[N_COINS] = old_balances
    for i in range(N_COINS):
        new_balances[i] -= _amounts[i]
    D1: uint256 = self.get_D_precisions(new_balances, amp)
    ys: uint256 = (D0 + D1) / N_COINS

    lp_token: address = self.lp_token
    token_supply: uint256 = ERC20(lp_token).totalSupply()
    assert token_supply != 0  # dev: zero total supply

    _fee: uint256 = self.fee * N_COINS / (4 * (N_COINS - 1))
    _feemul: uint256 = self.offpeg_fee_multiplier
    _admin_fee: uint256 = self.admin_fee
    fees: uint256[N_COINS] = empty(uint256[N_COINS])
    for i in range(N_COINS):
        ideal_balance: uint256 = D1 * old_balances[i] / D0
        new_balance: uint256 = new_balances[i]
        difference: uint256 = 0
        if ideal_balance > new_balance:
            difference = ideal_balance - new_balance
        else:
            difference = new_balance - ideal_balance
        xs: uint256 = new_balance + old_balances[i]
        fees[i] = self._dynamic_fee(xs, ys, _fee, _feemul) * difference / FEE_DENOMINATOR
        if _admin_fee != 0:
            self.admin_balances[i] += fees[i] * _admin_fee / FEE_DENOMINATOR
        new_balances[i] -= fees[i]
    D2: uint256 = self.get_D_precisions(new_balances, amp)

    token_amount: uint256 = (D0 - D2) * token_supply / D0
    assert token_amount != 0  # dev: zero tokens burned
    assert token_amount <= _max_burn_amount, "Slippage screwed you"

    CurveToken(lp_token).burnFrom(msg.sender, token_amount)  # dev: insufficient funds

    lending_pool: address = ZERO_ADDRESS
    if _use_underlying:
        lending_pool = self.aave_lending_pool

    for i in range(N_COINS):
        amount: uint256 = _amounts[i]
        if amount != 0:
            if _use_underlying:
                LendingPool(lending_pool).withdraw(self.underlying_coins[i], amount, msg.sender)
            else:
                assert ERC20(self.coins[i]).transfer(msg.sender, amount)

    log RemoveLiquidityImbalance(msg.sender, _amounts, fees, D1, token_supply - token_amount)

    return token_amount


@pure
@internal
def get_y_D(A_: uint256, i: int128, xp: uint256[N_COINS], D: uint256) -> uint256:
    """
    Calculate x[i] if one reduces D from being calculated for xp to D

    Done by solving quadratic equation iteratively.
    x_1**2 + x1 * (sum' - (A*n**n - 1) * D / (A * n**n)) = D ** (n + 1) / (n ** (2 * n) * prod' * A)
    x_1**2 + b*x_1 = c

    x_1 = (x_1**2 + c) / (2*x_1 + b)
    """
    # x in the input is converted to the same price/precision

    assert i >= 0       # dev: i below zero
    assert i < N_COINS  # dev: i above N_COINS

    Ann: uint256 = A_ * N_COINS
    c: uint256 = D
    S_: uint256 = 0
    _x: uint256 = 0
    y_prev: uint256 = 0

    for _i in range(N_COINS):
        if _i != i:
            _x = xp[_i]
        else:
            continue
        S_ += _x
        c = c * D / (_x * N_COINS)
    c = c * D * A_PRECISION / (Ann * N_COINS)
    b: uint256 = S_ + D * A_PRECISION / Ann
    y: uint256 = D

    for _i in range(255):
        y_prev = y
        y = (y*y + c) / (2 * y + b - D)
        # Equality with the precision of 1
        if y > y_prev:
            if y - y_prev <= 1:
                return y
        else:
            if y_prev - y <= 1:
                return y
    raise


@view
@internal
def _calc_withdraw_one_coin(_token_amount: uint256, i: int128) -> uint256:
    # First, need to calculate
    # * Get current D
    # * Solve Eqn against y_i for D - _token_amount
    amp: uint256 = self._A()
    xp: uint256[N_COINS] = self._balances()
    precisions: uint256[N_COINS] = PRECISION_MUL

    for j in range(N_COINS):
        xp[j] *= precisions[j]

    D0: uint256 = self.get_D(xp, amp)
    D1: uint256 = D0 - _token_amount * D0 / ERC20(self.lp_token).totalSupply()
    new_y: uint256 = self.get_y_D(amp, i, xp, D1)

    xp_reduced: uint256[N_COINS] = xp
    ys: uint256 = (D0 + D1) / (2 * N_COINS)

    _fee: uint256 = self.fee * N_COINS / (4 * (N_COINS - 1))
    feemul: uint256 = self.offpeg_fee_multiplier
    for j in range(N_COINS):
        dx_expected: uint256 = 0
        xavg: uint256 = 0
        if j == i:
            dx_expected = xp[j] * D1 / D0 - new_y
            xavg = (xp[j] + new_y) / 2
        else:
            dx_expected = xp[j] - xp[j] * D1 / D0
            xavg = xp[j]
        xp_reduced[j] -= self._dynamic_fee(xavg, ys, _fee, feemul) * dx_expected / FEE_DENOMINATOR

    dy: uint256 = xp_reduced[i] - self.get_y_D(amp, i, xp_reduced, D1)

    return (dy - 1) / precisions[i]


@view
@external
def calc_withdraw_one_coin(_token_amount: uint256, i: int128) -> uint256:
    """
    @notice Calculate the amount received when withdrawing a single coin
    @dev Result is the same for underlying or wrapped asset withdrawals
    @param _token_amount Amount of LP tokens to burn in the withdrawal
    @param i Index value of the coin to withdraw
    @return Amount of coin received
    """
    return self._calc_withdraw_one_coin(_token_amount, i)


@external
@nonreentrant('lock')
def remove_liquidity_one_coin(
    _token_amount: uint256,
    i: int128,
    _min_amount: uint256,
    _use_underlying: bool = False
) -> uint256:
    """
    @notice Withdraw a single coin from the pool
    @param _token_amount Amount of LP tokens to burn in the withdrawal
    @param i Index value of the coin to withdraw
    @param _min_amount Minimum amount of coin to receive
    @param _use_underlying If True, withdraw underlying assets instead of aTokens
    @return Amount of coin received
    """
    assert not self.is_killed  # dev: is killed

    dy: uint256 = self._calc_withdraw_one_coin(_token_amount, i)
    assert dy >= _min_amount, "Not enough coins removed"

    CurveToken(self.lp_token).burnFrom(msg.sender, _token_amount)  # dev: insufficient funds

    if _use_underlying:
        LendingPool(self.aave_lending_pool).withdraw(self.underlying_coins[i], dy, msg.sender)
    else:
        assert ERC20(self.coins[i]).transfer(msg.sender, dy)

    log RemoveLiquidityOne(msg.sender, _token_amount, dy)

    return dy


### Admin functions ###

@external
def ramp_A(_future_A: uint256, _future_time: uint256):
    assert msg.sender == self.owner  # dev: only owner
    assert block.timestamp >= self.initial_A_time + MIN_RAMP_TIME
    assert _future_time >= block.timestamp + MIN_RAMP_TIME  # dev: insufficient time

    _initial_A: uint256 = self._A()
    _future_A_p: uint256 = _future_A * A_PRECISION

    assert _future_A > 0 and _future_A < MAX_A
    if _future_A_p < _initial_A:
        assert _future_A_p * MAX_A_CHANGE >= _initial_A
    else:
        assert _future_A_p <= _initial_A * MAX_A_CHANGE

    self.initial_A = _initial_A
    self.future_A = _future_A_p
    self.initial_A_time = block.timestamp
    self.future_A_time = _future_time

    log RampA(_initial_A, _future_A_p, block.timestamp, _future_time)


@external
def stop_ramp_A():
    assert msg.sender == self.owner  # dev: only owner

    current_A: uint256 = self._A()
    self.initial_A = current_A
    self.future_A = current_A
    self.initial_A_time = block.timestamp
    self.future_A_time = block.timestamp
    # now (block.timestamp < t1) is always False, so we return saved A

    log StopRampA(current_A, block.timestamp)


@external
def commit_new_fee(new_fee: uint256, new_admin_fee: uint256, new_offpeg_fee_multiplier: uint256):
    assert msg.sender == self.owner  # dev: only owner
    assert self.admin_actions_deadline == 0  # dev: active action
    assert new_fee <= MAX_FEE  # dev: fee exceeds maximum
    assert new_admin_fee <= MAX_ADMIN_FEE  # dev: admin fee exceeds maximum
    assert new_offpeg_fee_multiplier * new_fee <= MAX_FEE * FEE_DENOMINATOR  # dev: offpeg multiplier exceeds maximum

    _deadline: uint256 = block.timestamp + ADMIN_ACTIONS_DELAY
    self.admin_actions_deadline = _deadline
    self.future_fee = new_fee
    self.future_admin_fee = new_admin_fee
    self.future_offpeg_fee_multiplier = new_offpeg_fee_multiplier

    log CommitNewFee(_deadline, new_fee, new_admin_fee, new_offpeg_fee_multiplier)


@external
def apply_new_fee():
    assert msg.sender == self.owner  # dev: only owner
    assert block.timestamp >= self.admin_actions_deadline  # dev: insufficient time
    assert self.admin_actions_deadline != 0  # dev: no active action

    self.admin_actions_deadline = 0
    _fee: uint256 = self.future_fee
    _admin_fee: uint256 = self.future_admin_fee
    _fml: uint256 = self.future_offpeg_fee_multiplier
    self.fee = _fee
    self.admin_fee = _admin_fee
    self.offpeg_fee_multiplier = _fml

    log NewFee(_fee, _admin_fee, _fml)


@external
def revert_new_parameters():
    assert msg.sender == self.owner  # dev: only owner

    self.admin_actions_deadline = 0


@external
def commit_transfer_ownership(_owner: address):
    assert msg.sender == self.owner  # dev: only owner
    assert self.transfer_ownership_deadline == 0  # dev: active transfer

    _deadline: uint256 = block.timestamp + ADMIN_ACTIONS_DELAY
    self.transfer_ownership_deadline = _deadline
    self.future_owner = _owner

    log CommitNewAdmin(_deadline, _owner)


@external
def apply_transfer_ownership():
    assert msg.sender == self.owner  # dev: only owner
    assert block.timestamp >= self.transfer_ownership_deadline  # dev: insufficient time
    assert self.transfer_ownership_deadline != 0  # dev: no active transfer

    self.transfer_ownership_deadline = 0
    _owner: address = self.future_owner
    self.owner = _owner

    log NewAdmin(_owner)


@external
def revert_transfer_ownership():
    assert msg.sender == self.owner  # dev: only owner

    self.transfer_ownership_deadline = 0


@external
def withdraw_admin_fees():
    assert msg.sender == self.owner  # dev: only owner

    for i in range(N_COINS):
        value: uint256 = self.admin_balances[i]
        if value != 0:
            assert ERC20(self.coins[i]).transfer(msg.sender, value)
            self.admin_balances[i] = 0


@external
def donate_admin_fees():
    """
    Just in case admin balances somehow become higher than total (rounding error?)
    this can be used to fix the state, too
    """
    assert msg.sender == self.owner  # dev: only owner
    self.admin_balances = empty(uint256[N_COINS])


@external
def kill_me():
    assert msg.sender == self.owner  # dev: only owner
    assert self.kill_deadline > block.timestamp  # dev: deadline has passed
    self.is_killed = True


@external
def unkill_me():
    assert msg.sender == self.owner  # dev: only owner
    self.is_killed = False


@external
def set_aave_referral(referral_code: uint256):
    assert msg.sender == self.owner  # dev: only owner
    assert referral_code < 2 ** 16  # dev: uint16 overflow
    self.aave_referral = referral_code

// SPDX-License-Identifier: agpl-3.0
pragma solidity 0.6.12;
import './BaseImmutableAdminUpgradeabilityProxy.sol';
import '../../../dependencies/openzeppelin/upgradeability/InitializableUpgradeabilityProxy.sol';
/**
 * @title InitializableAdminUpgradeabilityProxy
 * @dev Extends BaseAdminUpgradeabilityProxy with an initializer function
 */
contract InitializableImmutableAdminUpgradeabilityProxy is
  BaseImmutableAdminUpgradeabilityProxy,
  InitializableUpgradeabilityProxy
{
  constructor(address admin) public BaseImmutableAdminUpgradeabilityProxy(admin) {}
  /**
   * @dev Only fall back when the sender is not the admin.
   */
  function _willFallback() internal override(BaseImmutableAdminUpgradeabilityProxy, Proxy) {
    BaseImmutableAdminUpgradeabilityProxy._willFallback();
  }
}
// SPDX-License-Identifier: agpl-3.0
pragma solidity 0.6.12;
import '../../../dependencies/openzeppelin/upgradeability/BaseUpgradeabilityProxy.sol';
/**
 * @title BaseImmutableAdminUpgradeabilityProxy
 * @author Aave, inspired by the OpenZeppelin upgradeability proxy pattern
 * @dev This contract combines an upgradeability proxy with an authorization
 * mechanism for administrative tasks. The admin role is stored in an immutable, which
 * helps saving transactions costs
 * All external functions in this contract must be guarded by the
 * `ifAdmin` modifier. See ethereum/solidity#3864 for a Solidity
 * feature proposal that would enable this to be done automatically.
 */
contract BaseImmutableAdminUpgradeabilityProxy is BaseUpgradeabilityProxy {
  address immutable ADMIN;
  constructor(address admin) public {
    ADMIN = admin;
  }
  modifier ifAdmin() {
    if (msg.sender == ADMIN) {
      _;
    } else {
      _fallback();
    }
  }
  /**
   * @return The address of the proxy admin.
   */
  function admin() external ifAdmin returns (address) {
    return ADMIN;
  }
  /**
   * @return The address of the implementation.
   */
  function implementation() external ifAdmin returns (address) {
    return _implementation();
  }
  /**
   * @dev Upgrade the backing implementation of the proxy.
   * Only the admin can call this function.
   * @param newImplementation Address of the new implementation.
   */
  function upgradeTo(address newImplementation) external ifAdmin {
    _upgradeTo(newImplementation);
  }
  /**
   * @dev Upgrade the backing implementation of the proxy and call a function
   * on the new implementation.
   * This is useful to initialize the proxied contract.
   * @param newImplementation Address of the new implementation.
   * @param data Data to send as msg.data in the low level call.
   * It should include the signature and the parameters of the function to be called, as described in
   * https://solidity.readthedocs.io/en/v0.4.24/abi-spec.html#function-selector-and-argument-encoding.
   */
  function upgradeToAndCall(address newImplementation, bytes calldata data)
    external
    payable
    ifAdmin
  {
    _upgradeTo(newImplementation);
    (bool success, ) = newImplementation.delegatecall(data);
    require(success);
  }
  /**
   * @dev Only fall back when the sender is not the admin.
   */
  function _willFallback() internal virtual override {
    require(msg.sender != ADMIN, 'Cannot call fallback function from the proxy admin');
    super._willFallback();
  }
}
// SPDX-License-Identifier: agpl-3.0
pragma solidity 0.6.12;
import './Proxy.sol';
import '../contracts/Address.sol';
/**
 * @title BaseUpgradeabilityProxy
 * @dev This contract implements a proxy that allows to change the
 * implementation address to which it will delegate.
 * Such a change is called an implementation upgrade.
 */
contract BaseUpgradeabilityProxy is Proxy {
  /**
   * @dev Emitted when the implementation is upgraded.
   * @param implementation Address of the new implementation.
   */
  event Upgraded(address indexed implementation);
  /**
   * @dev Storage slot with the address of the current implementation.
   * This is the keccak-256 hash of "eip1967.proxy.implementation" subtracted by 1, and is
   * validated in the constructor.
   */
  bytes32 internal constant IMPLEMENTATION_SLOT = 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc;
  /**
   * @dev Returns the current implementation.
   * @return impl Address of the current implementation
   */
  function _implementation() internal override view returns (address impl) {
    bytes32 slot = IMPLEMENTATION_SLOT;
    //solium-disable-next-line
    assembly {
      impl := sload(slot)
    }
  }
  /**
   * @dev Upgrades the proxy to a new implementation.
   * @param newImplementation Address of the new implementation.
   */
  function _upgradeTo(address newImplementation) internal {
    _setImplementation(newImplementation);
    emit Upgraded(newImplementation);
  }
  /**
   * @dev Sets the implementation address of the proxy.
   * @param newImplementation Address of the new implementation.
   */
  function _setImplementation(address newImplementation) internal {
    require(
      Address.isContract(newImplementation),
      'Cannot set a proxy implementation to a non-contract address'
    );
    bytes32 slot = IMPLEMENTATION_SLOT;
    //solium-disable-next-line
    assembly {
      sstore(slot, newImplementation)
    }
  }
}
// SPDX-License-Identifier: agpl-3.0
pragma solidity ^0.6.0;
/**
 * @title Proxy
 * @dev Implements delegation of calls to other contracts, with proper
 * forwarding of return values and bubbling of failures.
 * It defines a fallback function that delegates all calls to the address
 * returned by the abstract _implementation() internal function.
 */
abstract contract Proxy {
  /**
   * @dev Fallback function.
   * Implemented entirely in `_fallback`.
   */
  fallback() external payable {
    _fallback();
  }
  /**
   * @return The Address of the implementation.
   */
  function _implementation() internal virtual view returns (address);
  /**
   * @dev Delegates execution to an implementation contract.
   * This is a low level function that doesn't return to its internal call site.
   * It will return to the external caller whatever the implementation returns.
   * @param implementation Address to delegate.
   */
  function _delegate(address implementation) internal {
    //solium-disable-next-line
    assembly {
      // Copy msg.data. We take full control of memory in this inline assembly
      // block because it will not return to Solidity code. We overwrite the
      // Solidity scratch pad at memory position 0.
      calldatacopy(0, 0, calldatasize())
      // Call the implementation.
      // out and outsize are 0 because we don't know the size yet.
      let result := delegatecall(gas(), implementation, 0, calldatasize(), 0, 0)
      // Copy the returned data.
      returndatacopy(0, 0, returndatasize())
      switch result
        // delegatecall returns 0 on error.
        case 0 {
          revert(0, returndatasize())
        }
        default {
          return(0, returndatasize())
        }
    }
  }
  /**
   * @dev Function that is run as the first thing in the fallback function.
   * Can be redefined in derived contracts to add functionality.
   * Redefinitions must call super._willFallback().
   */
  function _willFallback() internal virtual {}
  /**
   * @dev fallback implementation.
   * Extracted to enable manual triggering.
   */
  function _fallback() internal {
    _willFallback();
    _delegate(_implementation());
  }
}
// SPDX-License-Identifier: agpl-3.0
pragma solidity 0.6.12;
/**
 * @dev Collection of functions related to the address type
 */
library Address {
  /**
   * @dev Returns true if `account` is a contract.
   *
   * [IMPORTANT]
   * ====
   * It is unsafe to assume that an address for which this function returns
   * false is an externally-owned account (EOA) and not a contract.
   *
   * Among others, `isContract` will return false for the following
   * types of addresses:
   *
   *  - an externally-owned account
   *  - a contract in construction
   *  - an address where a contract will be created
   *  - an address where a contract lived, but was destroyed
   * ====
   */
  function isContract(address account) internal view returns (bool) {
    // According to EIP-1052, 0x0 is the value returned for not-yet created accounts
    // and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
    // for accounts without code, i.e. `keccak256('')`
    bytes32 codehash;
    bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
    // solhint-disable-next-line no-inline-assembly
    assembly {
      codehash := extcodehash(account)
    }
    return (codehash != accountHash && codehash != 0x0);
  }
  /**
   * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
   * `recipient`, forwarding all available gas and reverting on errors.
   *
   * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
   * of certain opcodes, possibly making contracts go over the 2300 gas limit
   * imposed by `transfer`, making them unable to receive funds via
   * `transfer`. {sendValue} removes this limitation.
   *
   * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
   *
   * IMPORTANT: because control is transferred to `recipient`, care must be
   * taken to not create reentrancy vulnerabilities. Consider using
   * {ReentrancyGuard} or the
   * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
   */
  function sendValue(address payable recipient, uint256 amount) internal {
    require(address(this).balance >= amount, 'Address: insufficient balance');
    // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
    (bool success, ) = recipient.call{value: amount}('');
    require(success, 'Address: unable to send value, recipient may have reverted');
  }
}
// SPDX-License-Identifier: agpl-3.0
pragma solidity 0.6.12;
import './BaseUpgradeabilityProxy.sol';
/**
 * @title InitializableUpgradeabilityProxy
 * @dev Extends BaseUpgradeabilityProxy with an initializer for initializing
 * implementation and init data.
 */
contract InitializableUpgradeabilityProxy is BaseUpgradeabilityProxy {
  /**
   * @dev Contract initializer.
   * @param _logic Address of the initial implementation.
   * @param _data Data to send as msg.data to the implementation to initialize the proxied contract.
   * It should include the signature and the parameters of the function to be called, as described in
   * https://solidity.readthedocs.io/en/v0.4.24/abi-spec.html#function-selector-and-argument-encoding.
   * This parameter is optional, if no data is given the initialization call to proxied contract will be skipped.
   */
  function initialize(address _logic, bytes memory _data) public payable {
    require(_implementation() == address(0));
    assert(IMPLEMENTATION_SLOT == bytes32(uint256(keccak256('eip1967.proxy.implementation')) - 1));
    _setImplementation(_logic);
    if (_data.length > 0) {
      (bool success, ) = _logic.delegatecall(_data);
      require(success);
    }
  }
}

// SPDX-License-Identifier: agpl-3.0
pragma solidity 0.6.12;
import './BaseImmutableAdminUpgradeabilityProxy.sol';
import '../../../dependencies/openzeppelin/upgradeability/InitializableUpgradeabilityProxy.sol';
/**
 * @title InitializableAdminUpgradeabilityProxy
 * @dev Extends BaseAdminUpgradeabilityProxy with an initializer function
 */
contract InitializableImmutableAdminUpgradeabilityProxy is
  BaseImmutableAdminUpgradeabilityProxy,
  InitializableUpgradeabilityProxy
{
  constructor(address admin) public BaseImmutableAdminUpgradeabilityProxy(admin) {}
  /**
   * @dev Only fall back when the sender is not the admin.
   */
  function _willFallback() internal override(BaseImmutableAdminUpgradeabilityProxy, Proxy) {
    BaseImmutableAdminUpgradeabilityProxy._willFallback();
  }
}
// SPDX-License-Identifier: agpl-3.0
pragma solidity 0.6.12;
import '../../../dependencies/openzeppelin/upgradeability/BaseUpgradeabilityProxy.sol';
/**
 * @title BaseImmutableAdminUpgradeabilityProxy
 * @author Aave, inspired by the OpenZeppelin upgradeability proxy pattern
 * @dev This contract combines an upgradeability proxy with an authorization
 * mechanism for administrative tasks. The admin role is stored in an immutable, which
 * helps saving transactions costs
 * All external functions in this contract must be guarded by the
 * `ifAdmin` modifier. See ethereum/solidity#3864 for a Solidity
 * feature proposal that would enable this to be done automatically.
 */
contract BaseImmutableAdminUpgradeabilityProxy is BaseUpgradeabilityProxy {
  address immutable ADMIN;
  constructor(address admin) public {
    ADMIN = admin;
  }
  modifier ifAdmin() {
    if (msg.sender == ADMIN) {
      _;
    } else {
      _fallback();
    }
  }
  /**
   * @return The address of the proxy admin.
   */
  function admin() external ifAdmin returns (address) {
    return ADMIN;
  }
  /**
   * @return The address of the implementation.
   */
  function implementation() external ifAdmin returns (address) {
    return _implementation();
  }
  /**
   * @dev Upgrade the backing implementation of the proxy.
   * Only the admin can call this function.
   * @param newImplementation Address of the new implementation.
   */
  function upgradeTo(address newImplementation) external ifAdmin {
    _upgradeTo(newImplementation);
  }
  /**
   * @dev Upgrade the backing implementation of the proxy and call a function
   * on the new implementation.
   * This is useful to initialize the proxied contract.
   * @param newImplementation Address of the new implementation.
   * @param data Data to send as msg.data in the low level call.
   * It should include the signature and the parameters of the function to be called, as described in
   * https://solidity.readthedocs.io/en/v0.4.24/abi-spec.html#function-selector-and-argument-encoding.
   */
  function upgradeToAndCall(address newImplementation, bytes calldata data)
    external
    payable
    ifAdmin
  {
    _upgradeTo(newImplementation);
    (bool success, ) = newImplementation.delegatecall(data);
    require(success);
  }
  /**
   * @dev Only fall back when the sender is not the admin.
   */
  function _willFallback() internal virtual override {
    require(msg.sender != ADMIN, 'Cannot call fallback function from the proxy admin');
    super._willFallback();
  }
}
// SPDX-License-Identifier: agpl-3.0
pragma solidity 0.6.12;
import './Proxy.sol';
import '../contracts/Address.sol';
/**
 * @title BaseUpgradeabilityProxy
 * @dev This contract implements a proxy that allows to change the
 * implementation address to which it will delegate.
 * Such a change is called an implementation upgrade.
 */
contract BaseUpgradeabilityProxy is Proxy {
  /**
   * @dev Emitted when the implementation is upgraded.
   * @param implementation Address of the new implementation.
   */
  event Upgraded(address indexed implementation);
  /**
   * @dev Storage slot with the address of the current implementation.
   * This is the keccak-256 hash of "eip1967.proxy.implementation" subtracted by 1, and is
   * validated in the constructor.
   */
  bytes32 internal constant IMPLEMENTATION_SLOT = 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc;
  /**
   * @dev Returns the current implementation.
   * @return impl Address of the current implementation
   */
  function _implementation() internal override view returns (address impl) {
    bytes32 slot = IMPLEMENTATION_SLOT;
    //solium-disable-next-line
    assembly {
      impl := sload(slot)
    }
  }
  /**
   * @dev Upgrades the proxy to a new implementation.
   * @param newImplementation Address of the new implementation.
   */
  function _upgradeTo(address newImplementation) internal {
    _setImplementation(newImplementation);
    emit Upgraded(newImplementation);
  }
  /**
   * @dev Sets the implementation address of the proxy.
   * @param newImplementation Address of the new implementation.
   */
  function _setImplementation(address newImplementation) internal {
    require(
      Address.isContract(newImplementation),
      'Cannot set a proxy implementation to a non-contract address'
    );
    bytes32 slot = IMPLEMENTATION_SLOT;
    //solium-disable-next-line
    assembly {
      sstore(slot, newImplementation)
    }
  }
}
// SPDX-License-Identifier: agpl-3.0
pragma solidity ^0.6.0;
/**
 * @title Proxy
 * @dev Implements delegation of calls to other contracts, with proper
 * forwarding of return values and bubbling of failures.
 * It defines a fallback function that delegates all calls to the address
 * returned by the abstract _implementation() internal function.
 */
abstract contract Proxy {
  /**
   * @dev Fallback function.
   * Implemented entirely in `_fallback`.
   */
  fallback() external payable {
    _fallback();
  }
  /**
   * @return The Address of the implementation.
   */
  function _implementation() internal virtual view returns (address);
  /**
   * @dev Delegates execution to an implementation contract.
   * This is a low level function that doesn't return to its internal call site.
   * It will return to the external caller whatever the implementation returns.
   * @param implementation Address to delegate.
   */
  function _delegate(address implementation) internal {
    //solium-disable-next-line
    assembly {
      // Copy msg.data. We take full control of memory in this inline assembly
      // block because it will not return to Solidity code. We overwrite the
      // Solidity scratch pad at memory position 0.
      calldatacopy(0, 0, calldatasize())
      // Call the implementation.
      // out and outsize are 0 because we don't know the size yet.
      let result := delegatecall(gas(), implementation, 0, calldatasize(), 0, 0)
      // Copy the returned data.
      returndatacopy(0, 0, returndatasize())
      switch result
        // delegatecall returns 0 on error.
        case 0 {
          revert(0, returndatasize())
        }
        default {
          return(0, returndatasize())
        }
    }
  }
  /**
   * @dev Function that is run as the first thing in the fallback function.
   * Can be redefined in derived contracts to add functionality.
   * Redefinitions must call super._willFallback().
   */
  function _willFallback() internal virtual {}
  /**
   * @dev fallback implementation.
   * Extracted to enable manual triggering.
   */
  function _fallback() internal {
    _willFallback();
    _delegate(_implementation());
  }
}
// SPDX-License-Identifier: agpl-3.0
pragma solidity 0.6.12;
/**
 * @dev Collection of functions related to the address type
 */
library Address {
  /**
   * @dev Returns true if `account` is a contract.
   *
   * [IMPORTANT]
   * ====
   * It is unsafe to assume that an address for which this function returns
   * false is an externally-owned account (EOA) and not a contract.
   *
   * Among others, `isContract` will return false for the following
   * types of addresses:
   *
   *  - an externally-owned account
   *  - a contract in construction
   *  - an address where a contract will be created
   *  - an address where a contract lived, but was destroyed
   * ====
   */
  function isContract(address account) internal view returns (bool) {
    // According to EIP-1052, 0x0 is the value returned for not-yet created accounts
    // and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
    // for accounts without code, i.e. `keccak256('')`
    bytes32 codehash;
    bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
    // solhint-disable-next-line no-inline-assembly
    assembly {
      codehash := extcodehash(account)
    }
    return (codehash != accountHash && codehash != 0x0);
  }
  /**
   * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
   * `recipient`, forwarding all available gas and reverting on errors.
   *
   * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
   * of certain opcodes, possibly making contracts go over the 2300 gas limit
   * imposed by `transfer`, making them unable to receive funds via
   * `transfer`. {sendValue} removes this limitation.
   *
   * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
   *
   * IMPORTANT: because control is transferred to `recipient`, care must be
   * taken to not create reentrancy vulnerabilities. Consider using
   * {ReentrancyGuard} or the
   * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
   */
  function sendValue(address payable recipient, uint256 amount) internal {
    require(address(this).balance >= amount, 'Address: insufficient balance');
    // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
    (bool success, ) = recipient.call{value: amount}('');
    require(success, 'Address: unable to send value, recipient may have reverted');
  }
}
// SPDX-License-Identifier: agpl-3.0
pragma solidity 0.6.12;
import './BaseUpgradeabilityProxy.sol';
/**
 * @title InitializableUpgradeabilityProxy
 * @dev Extends BaseUpgradeabilityProxy with an initializer for initializing
 * implementation and init data.
 */
contract InitializableUpgradeabilityProxy is BaseUpgradeabilityProxy {
  /**
   * @dev Contract initializer.
   * @param _logic Address of the initial implementation.
   * @param _data Data to send as msg.data to the implementation to initialize the proxied contract.
   * It should include the signature and the parameters of the function to be called, as described in
   * https://solidity.readthedocs.io/en/v0.4.24/abi-spec.html#function-selector-and-argument-encoding.
   * This parameter is optional, if no data is given the initialization call to proxied contract will be skipped.
   */
  function initialize(address _logic, bytes memory _data) public payable {
    require(_implementation() == address(0));
    assert(IMPLEMENTATION_SLOT == bytes32(uint256(keccak256('eip1967.proxy.implementation')) - 1));
    _setImplementation(_logic);
    if (_data.length > 0) {
      (bool success, ) = _logic.delegatecall(_data);
      require(success);
    }
  }
}

// SPDX-License-Identifier: agpl-3.0
pragma solidity 0.6.12;
import './BaseImmutableAdminUpgradeabilityProxy.sol';
import '../../../dependencies/openzeppelin/upgradeability/InitializableUpgradeabilityProxy.sol';
/**
 * @title InitializableAdminUpgradeabilityProxy
 * @dev Extends BaseAdminUpgradeabilityProxy with an initializer function
 */
contract InitializableImmutableAdminUpgradeabilityProxy is
  BaseImmutableAdminUpgradeabilityProxy,
  InitializableUpgradeabilityProxy
{
  constructor(address admin) public BaseImmutableAdminUpgradeabilityProxy(admin) {}
  /**
   * @dev Only fall back when the sender is not the admin.
   */
  function _willFallback() internal override(BaseImmutableAdminUpgradeabilityProxy, Proxy) {
    BaseImmutableAdminUpgradeabilityProxy._willFallback();
  }
}
// SPDX-License-Identifier: agpl-3.0
pragma solidity 0.6.12;
import '../../../dependencies/openzeppelin/upgradeability/BaseUpgradeabilityProxy.sol';
/**
 * @title BaseImmutableAdminUpgradeabilityProxy
 * @author Aave, inspired by the OpenZeppelin upgradeability proxy pattern
 * @dev This contract combines an upgradeability proxy with an authorization
 * mechanism for administrative tasks. The admin role is stored in an immutable, which
 * helps saving transactions costs
 * All external functions in this contract must be guarded by the
 * `ifAdmin` modifier. See ethereum/solidity#3864 for a Solidity
 * feature proposal that would enable this to be done automatically.
 */
contract BaseImmutableAdminUpgradeabilityProxy is BaseUpgradeabilityProxy {
  address immutable ADMIN;
  constructor(address admin) public {
    ADMIN = admin;
  }
  modifier ifAdmin() {
    if (msg.sender == ADMIN) {
      _;
    } else {
      _fallback();
    }
  }
  /**
   * @return The address of the proxy admin.
   */
  function admin() external ifAdmin returns (address) {
    return ADMIN;
  }
  /**
   * @return The address of the implementation.
   */
  function implementation() external ifAdmin returns (address) {
    return _implementation();
  }
  /**
   * @dev Upgrade the backing implementation of the proxy.
   * Only the admin can call this function.
   * @param newImplementation Address of the new implementation.
   */
  function upgradeTo(address newImplementation) external ifAdmin {
    _upgradeTo(newImplementation);
  }
  /**
   * @dev Upgrade the backing implementation of the proxy and call a function
   * on the new implementation.
   * This is useful to initialize the proxied contract.
   * @param newImplementation Address of the new implementation.
   * @param data Data to send as msg.data in the low level call.
   * It should include the signature and the parameters of the function to be called, as described in
   * https://solidity.readthedocs.io/en/v0.4.24/abi-spec.html#function-selector-and-argument-encoding.
   */
  function upgradeToAndCall(address newImplementation, bytes calldata data)
    external
    payable
    ifAdmin
  {
    _upgradeTo(newImplementation);
    (bool success, ) = newImplementation.delegatecall(data);
    require(success);
  }
  /**
   * @dev Only fall back when the sender is not the admin.
   */
  function _willFallback() internal virtual override {
    require(msg.sender != ADMIN, 'Cannot call fallback function from the proxy admin');
    super._willFallback();
  }
}
// SPDX-License-Identifier: agpl-3.0
pragma solidity 0.6.12;
import './Proxy.sol';
import '../contracts/Address.sol';
/**
 * @title BaseUpgradeabilityProxy
 * @dev This contract implements a proxy that allows to change the
 * implementation address to which it will delegate.
 * Such a change is called an implementation upgrade.
 */
contract BaseUpgradeabilityProxy is Proxy {
  /**
   * @dev Emitted when the implementation is upgraded.
   * @param implementation Address of the new implementation.
   */
  event Upgraded(address indexed implementation);
  /**
   * @dev Storage slot with the address of the current implementation.
   * This is the keccak-256 hash of "eip1967.proxy.implementation" subtracted by 1, and is
   * validated in the constructor.
   */
  bytes32 internal constant IMPLEMENTATION_SLOT = 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc;
  /**
   * @dev Returns the current implementation.
   * @return impl Address of the current implementation
   */
  function _implementation() internal override view returns (address impl) {
    bytes32 slot = IMPLEMENTATION_SLOT;
    //solium-disable-next-line
    assembly {
      impl := sload(slot)
    }
  }
  /**
   * @dev Upgrades the proxy to a new implementation.
   * @param newImplementation Address of the new implementation.
   */
  function _upgradeTo(address newImplementation) internal {
    _setImplementation(newImplementation);
    emit Upgraded(newImplementation);
  }
  /**
   * @dev Sets the implementation address of the proxy.
   * @param newImplementation Address of the new implementation.
   */
  function _setImplementation(address newImplementation) internal {
    require(
      Address.isContract(newImplementation),
      'Cannot set a proxy implementation to a non-contract address'
    );
    bytes32 slot = IMPLEMENTATION_SLOT;
    //solium-disable-next-line
    assembly {
      sstore(slot, newImplementation)
    }
  }
}
// SPDX-License-Identifier: agpl-3.0
pragma solidity ^0.6.0;
/**
 * @title Proxy
 * @dev Implements delegation of calls to other contracts, with proper
 * forwarding of return values and bubbling of failures.
 * It defines a fallback function that delegates all calls to the address
 * returned by the abstract _implementation() internal function.
 */
abstract contract Proxy {
  /**
   * @dev Fallback function.
   * Implemented entirely in `_fallback`.
   */
  fallback() external payable {
    _fallback();
  }
  /**
   * @return The Address of the implementation.
   */
  function _implementation() internal virtual view returns (address);
  /**
   * @dev Delegates execution to an implementation contract.
   * This is a low level function that doesn't return to its internal call site.
   * It will return to the external caller whatever the implementation returns.
   * @param implementation Address to delegate.
   */
  function _delegate(address implementation) internal {
    //solium-disable-next-line
    assembly {
      // Copy msg.data. We take full control of memory in this inline assembly
      // block because it will not return to Solidity code. We overwrite the
      // Solidity scratch pad at memory position 0.
      calldatacopy(0, 0, calldatasize())
      // Call the implementation.
      // out and outsize are 0 because we don't know the size yet.
      let result := delegatecall(gas(), implementation, 0, calldatasize(), 0, 0)
      // Copy the returned data.
      returndatacopy(0, 0, returndatasize())
      switch result
        // delegatecall returns 0 on error.
        case 0 {
          revert(0, returndatasize())
        }
        default {
          return(0, returndatasize())
        }
    }
  }
  /**
   * @dev Function that is run as the first thing in the fallback function.
   * Can be redefined in derived contracts to add functionality.
   * Redefinitions must call super._willFallback().
   */
  function _willFallback() internal virtual {}
  /**
   * @dev fallback implementation.
   * Extracted to enable manual triggering.
   */
  function _fallback() internal {
    _willFallback();
    _delegate(_implementation());
  }
}
// SPDX-License-Identifier: agpl-3.0
pragma solidity 0.6.12;
/**
 * @dev Collection of functions related to the address type
 */
library Address {
  /**
   * @dev Returns true if `account` is a contract.
   *
   * [IMPORTANT]
   * ====
   * It is unsafe to assume that an address for which this function returns
   * false is an externally-owned account (EOA) and not a contract.
   *
   * Among others, `isContract` will return false for the following
   * types of addresses:
   *
   *  - an externally-owned account
   *  - a contract in construction
   *  - an address where a contract will be created
   *  - an address where a contract lived, but was destroyed
   * ====
   */
  function isContract(address account) internal view returns (bool) {
    // According to EIP-1052, 0x0 is the value returned for not-yet created accounts
    // and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
    // for accounts without code, i.e. `keccak256('')`
    bytes32 codehash;
    bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
    // solhint-disable-next-line no-inline-assembly
    assembly {
      codehash := extcodehash(account)
    }
    return (codehash != accountHash && codehash != 0x0);
  }
  /**
   * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
   * `recipient`, forwarding all available gas and reverting on errors.
   *
   * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
   * of certain opcodes, possibly making contracts go over the 2300 gas limit
   * imposed by `transfer`, making them unable to receive funds via
   * `transfer`. {sendValue} removes this limitation.
   *
   * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
   *
   * IMPORTANT: because control is transferred to `recipient`, care must be
   * taken to not create reentrancy vulnerabilities. Consider using
   * {ReentrancyGuard} or the
   * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
   */
  function sendValue(address payable recipient, uint256 amount) internal {
    require(address(this).balance >= amount, 'Address: insufficient balance');
    // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
    (bool success, ) = recipient.call{value: amount}('');
    require(success, 'Address: unable to send value, recipient may have reverted');
  }
}
// SPDX-License-Identifier: agpl-3.0
pragma solidity 0.6.12;
import './BaseUpgradeabilityProxy.sol';
/**
 * @title InitializableUpgradeabilityProxy
 * @dev Extends BaseUpgradeabilityProxy with an initializer for initializing
 * implementation and init data.
 */
contract InitializableUpgradeabilityProxy is BaseUpgradeabilityProxy {
  /**
   * @dev Contract initializer.
   * @param _logic Address of the initial implementation.
   * @param _data Data to send as msg.data to the implementation to initialize the proxied contract.
   * It should include the signature and the parameters of the function to be called, as described in
   * https://solidity.readthedocs.io/en/v0.4.24/abi-spec.html#function-selector-and-argument-encoding.
   * This parameter is optional, if no data is given the initialization call to proxied contract will be skipped.
   */
  function initialize(address _logic, bytes memory _data) public payable {
    require(_implementation() == address(0));
    assert(IMPLEMENTATION_SLOT == bytes32(uint256(keccak256('eip1967.proxy.implementation')) - 1));
    _setImplementation(_logic);
    if (_data.length > 0) {
      (bool success, ) = _logic.delegatecall(_data);
      require(success);
    }
  }
}

// SPDX-License-Identifier: agpl-3.0
pragma solidity 0.6.12;
import './BaseImmutableAdminUpgradeabilityProxy.sol';
import '../../../dependencies/openzeppelin/upgradeability/InitializableUpgradeabilityProxy.sol';
/**
 * @title InitializableAdminUpgradeabilityProxy
 * @dev Extends BaseAdminUpgradeabilityProxy with an initializer function
 */
contract InitializableImmutableAdminUpgradeabilityProxy is
  BaseImmutableAdminUpgradeabilityProxy,
  InitializableUpgradeabilityProxy
{
  constructor(address admin) public BaseImmutableAdminUpgradeabilityProxy(admin) {}
  /**
   * @dev Only fall back when the sender is not the admin.
   */
  function _willFallback() internal override(BaseImmutableAdminUpgradeabilityProxy, Proxy) {
    BaseImmutableAdminUpgradeabilityProxy._willFallback();
  }
}
// SPDX-License-Identifier: agpl-3.0
pragma solidity 0.6.12;
import '../../../dependencies/openzeppelin/upgradeability/BaseUpgradeabilityProxy.sol';
/**
 * @title BaseImmutableAdminUpgradeabilityProxy
 * @author Aave, inspired by the OpenZeppelin upgradeability proxy pattern
 * @dev This contract combines an upgradeability proxy with an authorization
 * mechanism for administrative tasks. The admin role is stored in an immutable, which
 * helps saving transactions costs
 * All external functions in this contract must be guarded by the
 * `ifAdmin` modifier. See ethereum/solidity#3864 for a Solidity
 * feature proposal that would enable this to be done automatically.
 */
contract BaseImmutableAdminUpgradeabilityProxy is BaseUpgradeabilityProxy {
  address immutable ADMIN;
  constructor(address admin) public {
    ADMIN = admin;
  }
  modifier ifAdmin() {
    if (msg.sender == ADMIN) {
      _;
    } else {
      _fallback();
    }
  }
  /**
   * @return The address of the proxy admin.
   */
  function admin() external ifAdmin returns (address) {
    return ADMIN;
  }
  /**
   * @return The address of the implementation.
   */
  function implementation() external ifAdmin returns (address) {
    return _implementation();
  }
  /**
   * @dev Upgrade the backing implementation of the proxy.
   * Only the admin can call this function.
   * @param newImplementation Address of the new implementation.
   */
  function upgradeTo(address newImplementation) external ifAdmin {
    _upgradeTo(newImplementation);
  }
  /**
   * @dev Upgrade the backing implementation of the proxy and call a function
   * on the new implementation.
   * This is useful to initialize the proxied contract.
   * @param newImplementation Address of the new implementation.
   * @param data Data to send as msg.data in the low level call.
   * It should include the signature and the parameters of the function to be called, as described in
   * https://solidity.readthedocs.io/en/v0.4.24/abi-spec.html#function-selector-and-argument-encoding.
   */
  function upgradeToAndCall(address newImplementation, bytes calldata data)
    external
    payable
    ifAdmin
  {
    _upgradeTo(newImplementation);
    (bool success, ) = newImplementation.delegatecall(data);
    require(success);
  }
  /**
   * @dev Only fall back when the sender is not the admin.
   */
  function _willFallback() internal virtual override {
    require(msg.sender != ADMIN, 'Cannot call fallback function from the proxy admin');
    super._willFallback();
  }
}
// SPDX-License-Identifier: agpl-3.0
pragma solidity 0.6.12;
import './Proxy.sol';
import '../contracts/Address.sol';
/**
 * @title BaseUpgradeabilityProxy
 * @dev This contract implements a proxy that allows to change the
 * implementation address to which it will delegate.
 * Such a change is called an implementation upgrade.
 */
contract BaseUpgradeabilityProxy is Proxy {
  /**
   * @dev Emitted when the implementation is upgraded.
   * @param implementation Address of the new implementation.
   */
  event Upgraded(address indexed implementation);
  /**
   * @dev Storage slot with the address of the current implementation.
   * This is the keccak-256 hash of "eip1967.proxy.implementation" subtracted by 1, and is
   * validated in the constructor.
   */
  bytes32 internal constant IMPLEMENTATION_SLOT = 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc;
  /**
   * @dev Returns the current implementation.
   * @return impl Address of the current implementation
   */
  function _implementation() internal override view returns (address impl) {
    bytes32 slot = IMPLEMENTATION_SLOT;
    //solium-disable-next-line
    assembly {
      impl := sload(slot)
    }
  }
  /**
   * @dev Upgrades the proxy to a new implementation.
   * @param newImplementation Address of the new implementation.
   */
  function _upgradeTo(address newImplementation) internal {
    _setImplementation(newImplementation);
    emit Upgraded(newImplementation);
  }
  /**
   * @dev Sets the implementation address of the proxy.
   * @param newImplementation Address of the new implementation.
   */
  function _setImplementation(address newImplementation) internal {
    require(
      Address.isContract(newImplementation),
      'Cannot set a proxy implementation to a non-contract address'
    );
    bytes32 slot = IMPLEMENTATION_SLOT;
    //solium-disable-next-line
    assembly {
      sstore(slot, newImplementation)
    }
  }
}
// SPDX-License-Identifier: agpl-3.0
pragma solidity ^0.6.0;
/**
 * @title Proxy
 * @dev Implements delegation of calls to other contracts, with proper
 * forwarding of return values and bubbling of failures.
 * It defines a fallback function that delegates all calls to the address
 * returned by the abstract _implementation() internal function.
 */
abstract contract Proxy {
  /**
   * @dev Fallback function.
   * Implemented entirely in `_fallback`.
   */
  fallback() external payable {
    _fallback();
  }
  /**
   * @return The Address of the implementation.
   */
  function _implementation() internal virtual view returns (address);
  /**
   * @dev Delegates execution to an implementation contract.
   * This is a low level function that doesn't return to its internal call site.
   * It will return to the external caller whatever the implementation returns.
   * @param implementation Address to delegate.
   */
  function _delegate(address implementation) internal {
    //solium-disable-next-line
    assembly {
      // Copy msg.data. We take full control of memory in this inline assembly
      // block because it will not return to Solidity code. We overwrite the
      // Solidity scratch pad at memory position 0.
      calldatacopy(0, 0, calldatasize())
      // Call the implementation.
      // out and outsize are 0 because we don't know the size yet.
      let result := delegatecall(gas(), implementation, 0, calldatasize(), 0, 0)
      // Copy the returned data.
      returndatacopy(0, 0, returndatasize())
      switch result
        // delegatecall returns 0 on error.
        case 0 {
          revert(0, returndatasize())
        }
        default {
          return(0, returndatasize())
        }
    }
  }
  /**
   * @dev Function that is run as the first thing in the fallback function.
   * Can be redefined in derived contracts to add functionality.
   * Redefinitions must call super._willFallback().
   */
  function _willFallback() internal virtual {}
  /**
   * @dev fallback implementation.
   * Extracted to enable manual triggering.
   */
  function _fallback() internal {
    _willFallback();
    _delegate(_implementation());
  }
}
// SPDX-License-Identifier: agpl-3.0
pragma solidity 0.6.12;
/**
 * @dev Collection of functions related to the address type
 */
library Address {
  /**
   * @dev Returns true if `account` is a contract.
   *
   * [IMPORTANT]
   * ====
   * It is unsafe to assume that an address for which this function returns
   * false is an externally-owned account (EOA) and not a contract.
   *
   * Among others, `isContract` will return false for the following
   * types of addresses:
   *
   *  - an externally-owned account
   *  - a contract in construction
   *  - an address where a contract will be created
   *  - an address where a contract lived, but was destroyed
   * ====
   */
  function isContract(address account) internal view returns (bool) {
    // According to EIP-1052, 0x0 is the value returned for not-yet created accounts
    // and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
    // for accounts without code, i.e. `keccak256('')`
    bytes32 codehash;
    bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
    // solhint-disable-next-line no-inline-assembly
    assembly {
      codehash := extcodehash(account)
    }
    return (codehash != accountHash && codehash != 0x0);
  }
  /**
   * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
   * `recipient`, forwarding all available gas and reverting on errors.
   *
   * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
   * of certain opcodes, possibly making contracts go over the 2300 gas limit
   * imposed by `transfer`, making them unable to receive funds via
   * `transfer`. {sendValue} removes this limitation.
   *
   * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
   *
   * IMPORTANT: because control is transferred to `recipient`, care must be
   * taken to not create reentrancy vulnerabilities. Consider using
   * {ReentrancyGuard} or the
   * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
   */
  function sendValue(address payable recipient, uint256 amount) internal {
    require(address(this).balance >= amount, 'Address: insufficient balance');
    // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
    (bool success, ) = recipient.call{value: amount}('');
    require(success, 'Address: unable to send value, recipient may have reverted');
  }
}
// SPDX-License-Identifier: agpl-3.0
pragma solidity 0.6.12;
import './BaseUpgradeabilityProxy.sol';
/**
 * @title InitializableUpgradeabilityProxy
 * @dev Extends BaseUpgradeabilityProxy with an initializer for initializing
 * implementation and init data.
 */
contract InitializableUpgradeabilityProxy is BaseUpgradeabilityProxy {
  /**
   * @dev Contract initializer.
   * @param _logic Address of the initial implementation.
   * @param _data Data to send as msg.data to the implementation to initialize the proxied contract.
   * It should include the signature and the parameters of the function to be called, as described in
   * https://solidity.readthedocs.io/en/v0.4.24/abi-spec.html#function-selector-and-argument-encoding.
   * This parameter is optional, if no data is given the initialization call to proxied contract will be skipped.
   */
  function initialize(address _logic, bytes memory _data) public payable {
    require(_implementation() == address(0));
    assert(IMPLEMENTATION_SLOT == bytes32(uint256(keccak256('eip1967.proxy.implementation')) - 1));
    _setImplementation(_logic);
    if (_data.length > 0) {
      (bool success, ) = _logic.delegatecall(_data);
      require(success);
    }
  }
}

// hevm: flattened sources of /nix/store/8xb41r4qd0cjb63wcrxf1qmfg88p0961-dss-6fd7de0/src/dai.sol
pragma solidity =0.5.12;

////// /nix/store/8xb41r4qd0cjb63wcrxf1qmfg88p0961-dss-6fd7de0/src/lib.sol
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

/* pragma solidity 0.5.12; */

contract LibNote {
    event LogNote(
        bytes4   indexed  sig,
        address  indexed  usr,
        bytes32  indexed  arg1,
        bytes32  indexed  arg2,
        bytes             data
    ) anonymous;

    modifier note {
        _;
        assembly {
            // log an 'anonymous' event with a constant 6 words of calldata
            // and four indexed topics: selector, caller, arg1 and arg2
            let mark := msize                         // end of memory ensures zero
            mstore(0x40, add(mark, 288))              // update free memory pointer
            mstore(mark, 0x20)                        // bytes type data offset
            mstore(add(mark, 0x20), 224)              // bytes size (padded)
            calldatacopy(add(mark, 0x40), 0, 224)     // bytes payload
            log4(mark, 288,                           // calldata
                 shl(224, shr(224, calldataload(0))), // msg.sig
                 caller,                              // msg.sender
                 calldataload(4),                     // arg1
                 calldataload(36)                     // arg2
                )
        }
    }
}

////// /nix/store/8xb41r4qd0cjb63wcrxf1qmfg88p0961-dss-6fd7de0/src/dai.sol
// Copyright (C) 2017, 2018, 2019 dbrock, rain, mrchico

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

/* pragma solidity 0.5.12; */

/* import "./lib.sol"; */

contract Dai is LibNote {
    // --- Auth ---
    mapping (address => uint) public wards;
    function rely(address guy) external note auth { wards[guy] = 1; }
    function deny(address guy) external note auth { wards[guy] = 0; }
    modifier auth {
        require(wards[msg.sender] == 1, "Dai/not-authorized");
        _;
    }

    // --- ERC20 Data ---
    string  public constant name     = "Dai Stablecoin";
    string  public constant symbol   = "DAI";
    string  public constant version  = "1";
    uint8   public constant decimals = 18;
    uint256 public totalSupply;

    mapping (address => uint)                      public balanceOf;
    mapping (address => mapping (address => uint)) public allowance;
    mapping (address => uint)                      public nonces;

    event Approval(address indexed src, address indexed guy, uint wad);
    event Transfer(address indexed src, address indexed dst, uint wad);

    // --- Math ---
    function add(uint x, uint y) internal pure returns (uint z) {
        require((z = x + y) >= x);
    }
    function sub(uint x, uint y) internal pure returns (uint z) {
        require((z = x - y) <= x);
    }

    // --- EIP712 niceties ---
    bytes32 public DOMAIN_SEPARATOR;
    // bytes32 public constant PERMIT_TYPEHASH = keccak256("Permit(address holder,address spender,uint256 nonce,uint256 expiry,bool allowed)");
    bytes32 public constant PERMIT_TYPEHASH = 0xea2aa0a1be11a07ed86d755c93467f4f82362b452371d1ba94d1715123511acb;

    constructor(uint256 chainId_) public {
        wards[msg.sender] = 1;
        DOMAIN_SEPARATOR = keccak256(abi.encode(
            keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"),
            keccak256(bytes(name)),
            keccak256(bytes(version)),
            chainId_,
            address(this)
        ));
    }

    // --- Token ---
    function transfer(address dst, uint wad) external returns (bool) {
        return transferFrom(msg.sender, dst, wad);
    }
    function transferFrom(address src, address dst, uint wad)
        public returns (bool)
    {
        require(balanceOf[src] >= wad, "Dai/insufficient-balance");
        if (src != msg.sender && allowance[src][msg.sender] != uint(-1)) {
            require(allowance[src][msg.sender] >= wad, "Dai/insufficient-allowance");
            allowance[src][msg.sender] = sub(allowance[src][msg.sender], wad);
        }
        balanceOf[src] = sub(balanceOf[src], wad);
        balanceOf[dst] = add(balanceOf[dst], wad);
        emit Transfer(src, dst, wad);
        return true;
    }
    function mint(address usr, uint wad) external auth {
        balanceOf[usr] = add(balanceOf[usr], wad);
        totalSupply    = add(totalSupply, wad);
        emit Transfer(address(0), usr, wad);
    }
    function burn(address usr, uint wad) external {
        require(balanceOf[usr] >= wad, "Dai/insufficient-balance");
        if (usr != msg.sender && allowance[usr][msg.sender] != uint(-1)) {
            require(allowance[usr][msg.sender] >= wad, "Dai/insufficient-allowance");
            allowance[usr][msg.sender] = sub(allowance[usr][msg.sender], wad);
        }
        balanceOf[usr] = sub(balanceOf[usr], wad);
        totalSupply    = sub(totalSupply, wad);
        emit Transfer(usr, address(0), wad);
    }
    function approve(address usr, uint wad) external returns (bool) {
        allowance[msg.sender][usr] = wad;
        emit Approval(msg.sender, usr, wad);
        return true;
    }

    // --- Alias ---
    function push(address usr, uint wad) external {
        transferFrom(msg.sender, usr, wad);
    }
    function pull(address usr, uint wad) external {
        transferFrom(usr, msg.sender, wad);
    }
    function move(address src, address dst, uint wad) external {
        transferFrom(src, dst, wad);
    }

    // --- Approve by signature ---
    function permit(address holder, address spender, uint256 nonce, uint256 expiry,
                    bool allowed, uint8 v, bytes32 r, bytes32 s) external
    {
        bytes32 digest =
            keccak256(abi.encodePacked(
                "\x19\x01",
                DOMAIN_SEPARATOR,
                keccak256(abi.encode(PERMIT_TYPEHASH,
                                     holder,
                                     spender,
                                     nonce,
                                     expiry,
                                     allowed))
        ));

        require(holder != address(0), "Dai/invalid-address-0");
        require(holder == ecrecover(digest, v, r, s), "Dai/invalid-permit");
        require(expiry == 0 || now <= expiry, "Dai/permit-expired");
        require(nonce == nonces[holder]++, "Dai/invalid-nonce");
        uint wad = allowed ? uint(-1) : 0;
        allowance[holder][spender] = wad;
        emit Approval(holder, spender, wad);
    }
}

// File: contracts/token/interfaces/IERC20Token.sol

pragma solidity 0.4.26;

/*
    ERC20 Standard Token interface
*/
contract IERC20Token {
    // these functions aren't abstract since the compiler emits automatically generated getter functions as external
    function name() public view returns (string) {this;}
    function symbol() public view returns (string) {this;}
    function decimals() public view returns (uint8) {this;}
    function totalSupply() public view returns (uint256) {this;}
    function balanceOf(address _owner) public view returns (uint256) {_owner; this;}
    function allowance(address _owner, address _spender) public view returns (uint256) {_owner; _spender; this;}

    function transfer(address _to, uint256 _value) public returns (bool success);
    function transferFrom(address _from, address _to, uint256 _value) public returns (bool success);
    function approve(address _spender, uint256 _value) public returns (bool success);
}

// File: contracts/IBancorNetwork.sol

pragma solidity 0.4.26;


/*
    Bancor Network interface
*/
contract IBancorNetwork {
    function convert2(
        IERC20Token[] _path,
        uint256 _amount,
        uint256 _minReturn,
        address _affiliateAccount,
        uint256 _affiliateFee
    ) public payable returns (uint256);

    function claimAndConvert2(
        IERC20Token[] _path,
        uint256 _amount,
        uint256 _minReturn,
        address _affiliateAccount,
        uint256 _affiliateFee
    ) public returns (uint256);

    function convertFor2(
        IERC20Token[] _path,
        uint256 _amount,
        uint256 _minReturn,
        address _for,
        address _affiliateAccount,
        uint256 _affiliateFee
    ) public payable returns (uint256);

    function claimAndConvertFor2(
        IERC20Token[] _path,
        uint256 _amount,
        uint256 _minReturn,
        address _for,
        address _affiliateAccount,
        uint256 _affiliateFee
    ) public returns (uint256);

    // deprecated, backward compatibility
    function convert(
        IERC20Token[] _path,
        uint256 _amount,
        uint256 _minReturn
    ) public payable returns (uint256);

    // deprecated, backward compatibility
    function claimAndConvert(
        IERC20Token[] _path,
        uint256 _amount,
        uint256 _minReturn
    ) public returns (uint256);

    // deprecated, backward compatibility
    function convertFor(
        IERC20Token[] _path,
        uint256 _amount,
        uint256 _minReturn,
        address _for
    ) public payable returns (uint256);

    // deprecated, backward compatibility
    function claimAndConvertFor(
        IERC20Token[] _path,
        uint256 _amount,
        uint256 _minReturn,
        address _for
    ) public returns (uint256);
}

// File: contracts/IConversionPathFinder.sol

pragma solidity 0.4.26;


/*
    Conversion Path Finder interface
*/
contract IConversionPathFinder {
    function findPath(address _sourceToken, address _targetToken) public view returns (address[] memory);
}

// File: contracts/utility/interfaces/IOwned.sol

pragma solidity 0.4.26;

/*
    Owned contract interface
*/
contract IOwned {
    // this function isn't abstract since the compiler emits automatically generated getter functions as external
    function owner() public view returns (address) {this;}

    function transferOwnership(address _newOwner) public;
    function acceptOwnership() public;
}

// File: contracts/utility/interfaces/ITokenHolder.sol

pragma solidity 0.4.26;



/*
    Token Holder interface
*/
contract ITokenHolder is IOwned {
    function withdrawTokens(IERC20Token _token, address _to, uint256 _amount) public;
}

// File: contracts/converter/interfaces/IConverterAnchor.sol

pragma solidity 0.4.26;



/*
    Converter Anchor interface
*/
contract IConverterAnchor is IOwned, ITokenHolder {
}

// File: contracts/utility/interfaces/IWhitelist.sol

pragma solidity 0.4.26;

/*
    Whitelist interface
*/
contract IWhitelist {
    function isWhitelisted(address _address) public view returns (bool);
}

// File: contracts/converter/interfaces/IConverter.sol

pragma solidity 0.4.26;





/*
    Converter interface
*/
contract IConverter is IOwned {
    function converterType() public pure returns (uint16);
    function anchor() public view returns (IConverterAnchor) {this;}
    function isActive() public view returns (bool);

    function rateAndFee(IERC20Token _sourceToken, IERC20Token _targetToken, uint256 _amount) public view returns (uint256, uint256);
    function convert(IERC20Token _sourceToken,
                     IERC20Token _targetToken,
                     uint256 _amount,
                     address _trader,
                     address _beneficiary) public payable returns (uint256);

    function conversionWhitelist() public view returns (IWhitelist) {this;}
    function conversionFee() public view returns (uint32) {this;}
    function maxConversionFee() public view returns (uint32) {this;}
    function reserveBalance(IERC20Token _reserveToken) public view returns (uint256);
    function() external payable;

    function transferAnchorOwnership(address _newOwner) public;
    function acceptAnchorOwnership() public;
    function setConversionFee(uint32 _conversionFee) public;
    function setConversionWhitelist(IWhitelist _whitelist) public;
    function withdrawTokens(IERC20Token _token, address _to, uint256 _amount) public;
    function withdrawETH(address _to) public;
    function addReserve(IERC20Token _token, uint32 _ratio) public;

    // deprecated, backward compatibility
    function token() public view returns (IConverterAnchor);
    function transferTokenOwnership(address _newOwner) public;
    function acceptTokenOwnership() public;
    function connectors(address _address) public view returns (uint256, uint32, bool, bool, bool);
    function getConnectorBalance(IERC20Token _connectorToken) public view returns (uint256);
    function connectorTokens(uint256 _index) public view returns (IERC20Token);
    function connectorTokenCount() public view returns (uint16);
}

// File: contracts/converter/interfaces/IBancorFormula.sol

pragma solidity 0.4.26;

/*
    Bancor Formula interface
*/
contract IBancorFormula {
    function purchaseRate(uint256 _supply,
                          uint256 _reserveBalance,
                          uint32 _reserveWeight,
                          uint256 _amount)
                          public view returns (uint256);

    function saleRate(uint256 _supply,
                      uint256 _reserveBalance,
                      uint32 _reserveWeight,
                      uint256 _amount)
                      public view returns (uint256);

    function crossReserveRate(uint256 _sourceReserveBalance,
                              uint32 _sourceReserveWeight,
                              uint256 _targetReserveBalance,
                              uint32 _targetReserveWeight,
                              uint256 _amount)
                              public view returns (uint256);

    function fundCost(uint256 _supply,
                      uint256 _reserveBalance,
                      uint32 _reserveRatio,
                      uint256 _amount)
                      public view returns (uint256);

    function liquidateRate(uint256 _supply,
                           uint256 _reserveBalance,
                           uint32 _reserveRatio,
                           uint256 _amount)
                           public view returns (uint256);
}

// File: contracts/utility/Owned.sol

pragma solidity 0.4.26;


/**
  * @dev Provides support and utilities for contract ownership
*/
contract Owned is IOwned {
    address public owner;
    address public newOwner;

    /**
      * @dev triggered when the owner is updated
      *
      * @param _prevOwner previous owner
      * @param _newOwner  new owner
    */
    event OwnerUpdate(address indexed _prevOwner, address indexed _newOwner);

    /**
      * @dev initializes a new Owned instance
    */
    constructor() public {
        owner = msg.sender;
    }

    // allows execution by the owner only
    modifier ownerOnly {
        _ownerOnly();
        _;
    }

    // error message binary size optimization
    function _ownerOnly() internal view {
        require(msg.sender == owner, "ERR_ACCESS_DENIED");
    }

    /**
      * @dev allows transferring the contract ownership
      * the new owner still needs to accept the transfer
      * can only be called by the contract owner
      *
      * @param _newOwner    new contract owner
    */
    function transferOwnership(address _newOwner) public ownerOnly {
        require(_newOwner != owner, "ERR_SAME_OWNER");
        newOwner = _newOwner;
    }

    /**
      * @dev used by a new owner to accept an ownership transfer
    */
    function acceptOwnership() public {
        require(msg.sender == newOwner, "ERR_ACCESS_DENIED");
        emit OwnerUpdate(owner, newOwner);
        owner = newOwner;
        newOwner = address(0);
    }
}

// File: contracts/utility/Utils.sol

pragma solidity 0.4.26;

/**
  * @dev Utilities & Common Modifiers
*/
contract Utils {
    // verifies that a value is greater than zero
    modifier greaterThanZero(uint256 _value) {
        _greaterThanZero(_value);
        _;
    }

    // error message binary size optimization
    function _greaterThanZero(uint256 _value) internal pure {
        require(_value > 0, "ERR_ZERO_VALUE");
    }

    // validates an address - currently only checks that it isn't null
    modifier validAddress(address _address) {
        _validAddress(_address);
        _;
    }

    // error message binary size optimization
    function _validAddress(address _address) internal pure {
        require(_address != address(0), "ERR_INVALID_ADDRESS");
    }

    // verifies that the address is different than this contract address
    modifier notThis(address _address) {
        _notThis(_address);
        _;
    }

    // error message binary size optimization
    function _notThis(address _address) internal view {
        require(_address != address(this), "ERR_ADDRESS_IS_SELF");
    }
}

// File: contracts/utility/interfaces/IContractRegistry.sol

pragma solidity 0.4.26;

/*
    Contract Registry interface
*/
contract IContractRegistry {
    function addressOf(bytes32 _contractName) public view returns (address);

    // deprecated, backward compatibility
    function getAddress(bytes32 _contractName) public view returns (address);
}

// File: contracts/utility/ContractRegistryClient.sol

pragma solidity 0.4.26;




/**
  * @dev Base contract for ContractRegistry clients
*/
contract ContractRegistryClient is Owned, Utils {
    bytes32 internal constant CONTRACT_REGISTRY = "ContractRegistry";
    bytes32 internal constant BANCOR_NETWORK = "BancorNetwork";
    bytes32 internal constant BANCOR_FORMULA = "BancorFormula";
    bytes32 internal constant CONVERTER_FACTORY = "ConverterFactory";
    bytes32 internal constant CONVERSION_PATH_FINDER = "ConversionPathFinder";
    bytes32 internal constant CONVERTER_UPGRADER = "BancorConverterUpgrader";
    bytes32 internal constant CONVERTER_REGISTRY = "BancorConverterRegistry";
    bytes32 internal constant CONVERTER_REGISTRY_DATA = "BancorConverterRegistryData";
    bytes32 internal constant BNT_TOKEN = "BNTToken";
    bytes32 internal constant BANCOR_X = "BancorX";
    bytes32 internal constant BANCOR_X_UPGRADER = "BancorXUpgrader";

    IContractRegistry public registry;      // address of the current contract-registry
    IContractRegistry public prevRegistry;  // address of the previous contract-registry
    bool public onlyOwnerCanUpdateRegistry; // only an owner can update the contract-registry

    /**
      * @dev verifies that the caller is mapped to the given contract name
      *
      * @param _contractName    contract name
    */
    modifier only(bytes32 _contractName) {
        _only(_contractName);
        _;
    }

    // error message binary size optimization
    function _only(bytes32 _contractName) internal view {
        require(msg.sender == addressOf(_contractName), "ERR_ACCESS_DENIED");
    }

    /**
      * @dev initializes a new ContractRegistryClient instance
      *
      * @param  _registry   address of a contract-registry contract
    */
    constructor(IContractRegistry _registry) internal validAddress(_registry) {
        registry = IContractRegistry(_registry);
        prevRegistry = IContractRegistry(_registry);
    }

    /**
      * @dev updates to the new contract-registry
     */
    function updateRegistry() public {
        // verify that this function is permitted
        require(msg.sender == owner || !onlyOwnerCanUpdateRegistry, "ERR_ACCESS_DENIED");

        // get the new contract-registry
        IContractRegistry newRegistry = IContractRegistry(addressOf(CONTRACT_REGISTRY));

        // verify that the new contract-registry is different and not zero
        require(newRegistry != address(registry) && newRegistry != address(0), "ERR_INVALID_REGISTRY");

        // verify that the new contract-registry is pointing to a non-zero contract-registry
        require(newRegistry.addressOf(CONTRACT_REGISTRY) != address(0), "ERR_INVALID_REGISTRY");

        // save a backup of the current contract-registry before replacing it
        prevRegistry = registry;

        // replace the current contract-registry with the new contract-registry
        registry = newRegistry;
    }

    /**
      * @dev restores the previous contract-registry
    */
    function restoreRegistry() public ownerOnly {
        // restore the previous contract-registry
        registry = prevRegistry;
    }

    /**
      * @dev restricts the permission to update the contract-registry
      *
      * @param _onlyOwnerCanUpdateRegistry  indicates whether or not permission is restricted to owner only
    */
    function restrictRegistryUpdate(bool _onlyOwnerCanUpdateRegistry) public ownerOnly {
        // change the permission to update the contract-registry
        onlyOwnerCanUpdateRegistry = _onlyOwnerCanUpdateRegistry;
    }

    /**
      * @dev returns the address associated with the given contract name
      *
      * @param _contractName    contract name
      *
      * @return contract address
    */
    function addressOf(bytes32 _contractName) internal view returns (address) {
        return registry.addressOf(_contractName);
    }
}

// File: contracts/utility/ReentrancyGuard.sol

pragma solidity 0.4.26;

/**
  * @dev ReentrancyGuard
  *
  * The contract provides protection against re-entrancy - calling a function (directly or
  * indirectly) from within itself.
*/
contract ReentrancyGuard {
    // true while protected code is being executed, false otherwise
    bool private locked = false;

    /**
      * @dev ensures instantiation only by sub-contracts
    */
    constructor() internal {}

    // protects a function against reentrancy attacks
    modifier protected() {
        _protected();
        locked = true;
        _;
        locked = false;
    }

    // error message binary size optimization
    function _protected() internal view {
        require(!locked, "ERR_REENTRANCY");
    }
}

// File: contracts/utility/TokenHandler.sol

pragma solidity 0.4.26;


contract TokenHandler {
    bytes4 private constant APPROVE_FUNC_SELECTOR = bytes4(keccak256("approve(address,uint256)"));
    bytes4 private constant TRANSFER_FUNC_SELECTOR = bytes4(keccak256("transfer(address,uint256)"));
    bytes4 private constant TRANSFER_FROM_FUNC_SELECTOR = bytes4(keccak256("transferFrom(address,address,uint256)"));

    /**
      * @dev executes the ERC20 token's `approve` function and reverts upon failure
      * the main purpose of this function is to prevent a non standard ERC20 token
      * from failing silently
      *
      * @param _token   ERC20 token address
      * @param _spender approved address
      * @param _value   allowance amount
    */
    function safeApprove(IERC20Token _token, address _spender, uint256 _value) internal {
       execute(_token, abi.encodeWithSelector(APPROVE_FUNC_SELECTOR, _spender, _value));
    }

    /**
      * @dev executes the ERC20 token's `transfer` function and reverts upon failure
      * the main purpose of this function is to prevent a non standard ERC20 token
      * from failing silently
      *
      * @param _token   ERC20 token address
      * @param _to      target address
      * @param _value   transfer amount
    */
    function safeTransfer(IERC20Token _token, address _to, uint256 _value) internal {
       execute(_token, abi.encodeWithSelector(TRANSFER_FUNC_SELECTOR, _to, _value));
    }

    /**
      * @dev executes the ERC20 token's `transferFrom` function and reverts upon failure
      * the main purpose of this function is to prevent a non standard ERC20 token
      * from failing silently
      *
      * @param _token   ERC20 token address
      * @param _from    source address
      * @param _to      target address
      * @param _value   transfer amount
    */
    function safeTransferFrom(IERC20Token _token, address _from, address _to, uint256 _value) internal {
       execute(_token, abi.encodeWithSelector(TRANSFER_FROM_FUNC_SELECTOR, _from, _to, _value));
    }

    /**
      * @dev executes a function on the ERC20 token and reverts upon failure
      * the main purpose of this function is to prevent a non standard ERC20 token
      * from failing silently
      *
      * @param _token   ERC20 token address
      * @param _data    data to pass in to the token's contract for execution
    */
    function execute(IERC20Token _token, bytes memory _data) private {
        uint256[1] memory ret = [uint256(1)];

        assembly {
            let success := call(
                gas,            // gas remaining
                _token,         // destination address
                0,              // no ether
                add(_data, 32), // input buffer (starts after the first 32 bytes in the `data` array)
                mload(_data),   // input length (loaded from the first 32 bytes in the `data` array)
                ret,            // output buffer
                32              // output length
            )
            if iszero(success) {
                revert(0, 0)
            }
        }

        require(ret[0] != 0, "ERR_TRANSFER_FAILED");
    }
}

// File: contracts/utility/TokenHolder.sol

pragma solidity 0.4.26;






/**
  * @dev We consider every contract to be a 'token holder' since it's currently not possible
  * for a contract to deny receiving tokens.
  *
  * The TokenHolder's contract sole purpose is to provide a safety mechanism that allows
  * the owner to send tokens that were sent to the contract by mistake back to their sender.
  *
  * Note that we use the non standard ERC-20 interface which has no return value for transfer
  * in order to support both non standard as well as standard token contracts.
  * see https://github.com/ethereum/solidity/issues/4116
*/
contract TokenHolder is ITokenHolder, TokenHandler, Owned, Utils {
    /**
      * @dev withdraws tokens held by the contract and sends them to an account
      * can only be called by the owner
      *
      * @param _token   ERC20 token contract address
      * @param _to      account to receive the new amount
      * @param _amount  amount to withdraw
    */
    function withdrawTokens(IERC20Token _token, address _to, uint256 _amount)
        public
        ownerOnly
        validAddress(_token)
        validAddress(_to)
        notThis(_to)
    {
        safeTransfer(_token, _to, _amount);
    }
}

// File: contracts/utility/SafeMath.sol

pragma solidity 0.4.26;

/**
  * @dev Library for basic math operations with overflow/underflow protection
*/
library SafeMath {
    /**
      * @dev returns the sum of _x and _y, reverts if the calculation overflows
      *
      * @param _x   value 1
      * @param _y   value 2
      *
      * @return sum
    */
    function add(uint256 _x, uint256 _y) internal pure returns (uint256) {
        uint256 z = _x + _y;
        require(z >= _x, "ERR_OVERFLOW");
        return z;
    }

    /**
      * @dev returns the difference of _x minus _y, reverts if the calculation underflows
      *
      * @param _x   minuend
      * @param _y   subtrahend
      *
      * @return difference
    */
    function sub(uint256 _x, uint256 _y) internal pure returns (uint256) {
        require(_x >= _y, "ERR_UNDERFLOW");
        return _x - _y;
    }

    /**
      * @dev returns the product of multiplying _x by _y, reverts if the calculation overflows
      *
      * @param _x   factor 1
      * @param _y   factor 2
      *
      * @return product
    */
    function mul(uint256 _x, uint256 _y) internal pure returns (uint256) {
        // gas optimization
        if (_x == 0)
            return 0;

        uint256 z = _x * _y;
        require(z / _x == _y, "ERR_OVERFLOW");
        return z;
    }

    /**
      * @dev Integer division of two numbers truncating the quotient, reverts on division by zero.
      *
      * @param _x   dividend
      * @param _y   divisor
      *
      * @return quotient
    */
    function div(uint256 _x, uint256 _y) internal pure returns (uint256) {
        require(_y > 0, "ERR_DIVIDE_BY_ZERO");
        uint256 c = _x / _y;
        return c;
    }
}

// File: contracts/token/interfaces/IEtherToken.sol

pragma solidity 0.4.26;


/*
    Ether Token interface
*/
contract IEtherToken is IERC20Token {
    function deposit() public payable;
    function withdraw(uint256 _amount) public;
    function depositTo(address _to) public payable;
    function withdrawTo(address _to, uint256 _amount) public;
}

// File: contracts/token/interfaces/ISmartToken.sol

pragma solidity 0.4.26;




/*
    Smart Token interface
*/
contract ISmartToken is IConverterAnchor, IERC20Token {
    function disableTransfers(bool _disable) public;
    function issue(address _to, uint256 _amount) public;
    function destroy(address _from, uint256 _amount) public;
}

// File: contracts/bancorx/interfaces/IBancorX.sol

pragma solidity 0.4.26;


contract IBancorX {
    function token() public view returns (IERC20Token) {this;}
    function xTransfer(bytes32 _toBlockchain, bytes32 _to, uint256 _amount, uint256 _id) public;
    function getXTransferAmount(uint256 _xTransferId, address _for) public view returns (uint256);
}

// File: contracts/BancorNetwork.sol

pragma solidity 0.4.26;













// interface of older converters for backward compatibility
contract ILegacyConverter {
    function change(IERC20Token _sourceToken, IERC20Token _targetToken, uint256 _amount, uint256 _minReturn) public returns (uint256);
}

/**
  * @dev The BancorNetwork contract is the main entry point for Bancor token conversions.
  * It also allows for the conversion of any token in the Bancor Network to any other token in a single
  * transaction by providing a conversion path.
  *
  * A note on Conversion Path: Conversion path is a data structure that is used when converting a token
  * to another token in the Bancor Network, when the conversion cannot necessarily be done by a single
  * converter and might require multiple 'hops'.
  * The path defines which converters should be used and what kind of conversion should be done in each step.
  *
  * The path format doesn't include complex structure; instead, it is represented by a single array
  * in which each 'hop' is represented by a 2-tuple - converter anchor & target token.
  * In addition, the first element is always the source token.
  * The converter anchor is only used as a pointer to a converter (since converter addresses are more
  * likely to change as opposed to anchor addresses).
  *
  * Format:
  * [source token, converter anchor, target token, converter anchor, target token...]
*/
contract BancorNetwork is IBancorNetwork, TokenHolder, ContractRegistryClient, ReentrancyGuard {
    using SafeMath for uint256;

    uint256 private constant CONVERSION_FEE_RESOLUTION = 1000000;
    uint256 private constant AFFILIATE_FEE_RESOLUTION = 1000000;
    address private constant ETH_RESERVE_ADDRESS = 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE;

    struct ConversionStep {
        IConverter converter;
        IConverterAnchor anchor;
        IERC20Token sourceToken;
        IERC20Token targetToken;
        address beneficiary;
        bool isV28OrHigherConverter;
        bool processAffiliateFee;
    }

    uint256 public maxAffiliateFee = 30000;     // maximum affiliate-fee

    mapping (address => bool) public etherTokens;       // list of all supported ether tokens

    /**
      * @dev triggered when a conversion between two tokens occurs
      *
      * @param _smartToken  anchor governed by the converter
      * @param _fromToken   source ERC20 token
      * @param _toToken     target ERC20 token
      * @param _fromAmount  amount converted, in the source token
      * @param _toAmount    amount returned, minus conversion fee
      * @param _trader      wallet that initiated the trade
    */
    event Conversion(
        address indexed _smartToken,
        address indexed _fromToken,
        address indexed _toToken,
        uint256 _fromAmount,
        uint256 _toAmount,
        address _trader
    );

    /**
      * @dev initializes a new BancorNetwork instance
      *
      * @param _registry    address of a contract registry contract
    */
    constructor(IContractRegistry _registry) ContractRegistryClient(_registry) public {
        etherTokens[ETH_RESERVE_ADDRESS] = true;
    }

    /**
      * @dev allows the owner to update the maximum affiliate-fee
      *
      * @param _maxAffiliateFee   maximum affiliate-fee
    */
    function setMaxAffiliateFee(uint256 _maxAffiliateFee)
        public
        ownerOnly
    {
        require(_maxAffiliateFee <= AFFILIATE_FEE_RESOLUTION, "ERR_INVALID_AFFILIATE_FEE");
        maxAffiliateFee = _maxAffiliateFee;
    }

    /**
      * @dev allows the owner to register/unregister ether tokens
      *
      * @param _token       ether token contract address
      * @param _register    true to register, false to unregister
    */
    function registerEtherToken(IEtherToken _token, bool _register)
        public
        ownerOnly
        validAddress(_token)
        notThis(_token)
    {
        etherTokens[_token] = _register;
    }

    /**
      * @dev returns the conversion path between two tokens in the network
      * note that this method is quite expensive in terms of gas and should generally be called off-chain
      *
      * @param _sourceToken source token address
      * @param _targetToken target token address
      *
      * @return conversion path between the two tokens
    */
    function conversionPath(IERC20Token _sourceToken, IERC20Token _targetToken) public view returns (address[]) {
        IConversionPathFinder pathFinder = IConversionPathFinder(addressOf(CONVERSION_PATH_FINDER));
        return pathFinder.findPath(_sourceToken, _targetToken);
    }

    /**
      * @dev returns the expected rate of converting a given amount on a given path
      * note that there is no support for circular paths
      *
      * @param _path        conversion path (see conversion path format above)
      * @param _amount      amount of _path[0] tokens received from the sender
      *
      * @return expected rate
    */
    function rateByPath(IERC20Token[] _path, uint256 _amount) public view returns (uint256) {
        uint256 amount;
        uint256 fee;
        uint256 supply;
        uint256 balance;
        uint32 weight;
        IConverter converter;
        IBancorFormula formula = IBancorFormula(addressOf(BANCOR_FORMULA));

        amount = _amount;

        // verify that the number of elements is larger than 2 and odd
        require(_path.length > 2 && _path.length % 2 == 1, "ERR_INVALID_PATH");

        // iterate over the conversion path
        for (uint256 i = 2; i < _path.length; i += 2) {
            IERC20Token sourceToken = _path[i - 2];
            IERC20Token anchor = _path[i - 1];
            IERC20Token targetToken = _path[i];

            converter = IConverter(IConverterAnchor(anchor).owner());

            // backward compatibility
            sourceToken = getConverterTokenAddress(converter, sourceToken);
            targetToken = getConverterTokenAddress(converter, targetToken);

            if (targetToken == anchor) { // buy the smart token
                // check if the current smart token has changed
                if (i < 3 || anchor != _path[i - 3])
                    supply = ISmartToken(anchor).totalSupply();

                // get the amount & the conversion fee
                balance = converter.getConnectorBalance(sourceToken);
                (, weight, , , ) = converter.connectors(sourceToken);
                amount = formula.purchaseRate(supply, balance, weight, amount);
                fee = amount.mul(converter.conversionFee()).div(CONVERSION_FEE_RESOLUTION);
                amount -= fee;

                // update the smart token supply for the next iteration
                supply = supply.add(amount);
            }
            else if (sourceToken == anchor) { // sell the smart token
                // check if the current smart token has changed
                if (i < 3 || anchor != _path[i - 3])
                    supply = ISmartToken(anchor).totalSupply();

                // get the amount & the conversion fee
                balance = converter.getConnectorBalance(targetToken);
                (, weight, , , ) = converter.connectors(targetToken);
                amount = formula.saleRate(supply, balance, weight, amount);
                fee = amount.mul(converter.conversionFee()).div(CONVERSION_FEE_RESOLUTION);
                amount -= fee;

                // update the smart token supply for the next iteration
                supply = supply.sub(amount);
            }
            else { // cross reserve conversion
                (amount, fee) = getReturn(converter, sourceToken, targetToken, amount);
            }
        }

        return amount;
    }

    /**
      * @dev converts the token to any other token in the bancor network by following
      * a predefined conversion path and transfers the result tokens to a target account
      * affiliate account/fee can also be passed in to receive a conversion fee (on top of the liquidity provider fees)
      * note that the network should already have been given allowance of the source token (if not ETH)
      *
      * @param _path                conversion path, see conversion path format above
      * @param _amount              amount to convert from, in the source token
      * @param _minReturn           if the conversion results in an amount smaller than the minimum return - it is cancelled, must be greater than zero
      * @param _beneficiary         account that will receive the conversion result or 0x0 to send the result to the sender account
      * @param _affiliateAccount    wallet address to receive the affiliate fee or 0x0 to disable affiliate fee
      * @param _affiliateFee        affiliate fee in PPM or 0 to disable affiliate fee
      *
      * @return amount of tokens received from the conversion
    */
    function convertByPath(IERC20Token[] _path, uint256 _amount, uint256 _minReturn, address _beneficiary, address _affiliateAccount, uint256 _affiliateFee)
        public
        payable
        protected
        greaterThanZero(_minReturn)
        returns (uint256)
    {
        // verify that the path contrains at least a single 'hop' and that the number of elements is odd
        require(_path.length > 2 && _path.length % 2 == 1, "ERR_INVALID_PATH");

        // validate msg.value and prepare the source token for the conversion
        handleSourceToken(_path[0], IConverterAnchor(_path[1]), _amount);

        // check if affiliate fee is enabled
        bool affiliateFeeEnabled = false;
        if (address(_affiliateAccount) == 0) {
            require(_affiliateFee == 0, "ERR_INVALID_AFFILIATE_FEE");
        }
        else {
            require(0 < _affiliateFee && _affiliateFee <= maxAffiliateFee, "ERR_INVALID_AFFILIATE_FEE");
            affiliateFeeEnabled = true;
        }

        // check if beneficiary is set
        address beneficiary = msg.sender;
        if (_beneficiary != address(0))
            beneficiary = _beneficiary;

        // convert and get the resulting amount
        ConversionStep[] memory data = createConversionData(_path, beneficiary, affiliateFeeEnabled);
        uint256 amount = doConversion(data, _amount, _minReturn, _affiliateAccount, _affiliateFee);

        // handle the conversion target tokens
        handleTargetToken(data, amount, beneficiary);

        return amount;
    }

    /**
      * @dev converts any other token to BNT in the bancor network by following
      a predefined conversion path and transfers the result to an account on a different blockchain
      * note that the network should already have been given allowance of the source token (if not ETH)
      *
      * @param _path                conversion path, see conversion path format above
      * @param _amount              amount to convert from, in the source token
      * @param _minReturn           if the conversion results in an amount smaller than the minimum return - it is cancelled, must be greater than zero
      * @param _targetBlockchain    blockchain BNT will be issued on
      * @param _targetAccount       address/account on the target blockchain to send the BNT to
      * @param _conversionId        pre-determined unique (if non zero) id which refers to this transaction
      *
      * @return the amount of BNT received from this conversion
    */
    function xConvert(
        IERC20Token[] _path,
        uint256 _amount,
        uint256 _minReturn,
        bytes32 _targetBlockchain,
        bytes32 _targetAccount,
        uint256 _conversionId
    )
        public
        payable
        returns (uint256)
    {
        return xConvert2(_path, _amount, _minReturn, _targetBlockchain, _targetAccount, _conversionId, address(0), 0);
    }

    /**
      * @dev converts any other token to BNT in the bancor network by following
      a predefined conversion path and transfers the result to an account on a different blockchain
      * note that the network should already have been given allowance of the source token (if not ETH)
      *
      * @param _path                conversion path, see conversion path format above
      * @param _amount              amount to convert from, in the source token
      * @param _minReturn           if the conversion results in an amount smaller than the minimum return - it is cancelled, must be greater than zero
      * @param _targetBlockchain    blockchain BNT will be issued on
      * @param _targetAccount       address/account on the target blockchain to send the BNT to
      * @param _conversionId        pre-determined unique (if non zero) id which refers to this transaction
      * @param _affiliateAccount    affiliate account
      * @param _affiliateFee        affiliate fee in PPM
      *
      * @return the amount of BNT received from this conversion
    */
    function xConvert2(
        IERC20Token[] _path,
        uint256 _amount,
        uint256 _minReturn,
        bytes32 _targetBlockchain,
        bytes32 _targetAccount,
        uint256 _conversionId,
        address _affiliateAccount,
        uint256 _affiliateFee
    )
        public
        payable
        greaterThanZero(_minReturn)
        returns (uint256)
    {
        IERC20Token targetToken = _path[_path.length - 1];
        IBancorX bancorX = IBancorX(addressOf(BANCOR_X));

        // verify that the destination token is BNT
        require(targetToken == addressOf(BNT_TOKEN), "ERR_INVALID_TARGET_TOKEN");

        // convert and get the resulting amount
        uint256 amount = convertByPath(_path, _amount, _minReturn, this, _affiliateAccount, _affiliateFee);

        // grant BancorX allowance
        ensureAllowance(targetToken, bancorX, amount);

        // transfer the resulting amount to BancorX
        bancorX.xTransfer(_targetBlockchain, _targetAccount, amount, _conversionId);

        return amount;
    }

    /**
      * @dev allows a user to convert a token that was sent from another blockchain into any other
      * token on the BancorNetwork
      * ideally this transaction is created before the previous conversion is even complete, so
      * so the input amount isn't known at that point - the amount is actually take from the
      * BancorX contract directly by specifying the conversion id
      *
      * @param _path            conversion path
      * @param _bancorX         address of the BancorX contract for the source token
      * @param _conversionId    pre-determined unique (if non zero) id which refers to this conversion
      * @param _minReturn       if the conversion results in an amount smaller than the minimum return - it is cancelled, must be nonzero
      * @param _beneficiary     wallet to receive the conversion result
      *
      * @return amount of tokens received from the conversion
    */
    function completeXConversion(IERC20Token[] _path, IBancorX _bancorX, uint256 _conversionId, uint256 _minReturn, address _beneficiary)
        public returns (uint256)
    {
        // verify that the source token is the BancorX token
        require(_path[0] == _bancorX.token(), "ERR_INVALID_SOURCE_TOKEN");

        // get conversion amount from BancorX contract
        uint256 amount = _bancorX.getXTransferAmount(_conversionId, msg.sender);

        // perform the conversion
        return convertByPath(_path, amount, _minReturn, _beneficiary, address(0), 0);
    }

    /**
      * @dev executes the actual conversion by following the conversion path
      *
      * @param _data                conversion data, see ConversionStep struct above
      * @param _amount              amount to convert from, in the source token
      * @param _minReturn           if the conversion results in an amount smaller than the minimum return - it is cancelled, must be greater than zero
      * @param _affiliateAccount    affiliate account
      * @param _affiliateFee        affiliate fee in PPM
      *
      * @return amount of tokens received from the conversion
    */
    function doConversion(
        ConversionStep[] _data,
        uint256 _amount,
        uint256 _minReturn,
        address _affiliateAccount,
        uint256 _affiliateFee
    ) private returns (uint256) {
        uint256 toAmount;
        uint256 fromAmount = _amount;

        // iterate over the conversion data
        for (uint256 i = 0; i < _data.length; i++) {
            ConversionStep memory stepData = _data[i];

            // newer converter
            if (stepData.isV28OrHigherConverter) {
                // transfer the tokens to the converter only if the network contract currently holds the tokens
                // not needed with ETH or if it's the first conversion step
                if (i != 0 && _data[i - 1].beneficiary == address(this) && !etherTokens[stepData.sourceToken])
                    safeTransfer(stepData.sourceToken, stepData.converter, fromAmount);
            }
            // older converter
            // if the source token is the smart token, no need to do any transfers as the converter controls it
            else if (stepData.sourceToken != ISmartToken(stepData.anchor)) {
                // grant allowance for it to transfer the tokens from the network contract
                ensureAllowance(stepData.sourceToken, stepData.converter, fromAmount);
            }

            // do the conversion
            if (!stepData.isV28OrHigherConverter)
                toAmount = ILegacyConverter(stepData.converter).change(stepData.sourceToken, stepData.targetToken, fromAmount, 1);
            else if (etherTokens[stepData.sourceToken])
                toAmount = stepData.converter.convert.value(msg.value)(stepData.sourceToken, stepData.targetToken, fromAmount, msg.sender, stepData.beneficiary);
            else
                toAmount = stepData.converter.convert(stepData.sourceToken, stepData.targetToken, fromAmount, msg.sender, stepData.beneficiary);

            // pay affiliate-fee if needed
            if (stepData.processAffiliateFee) {
                uint256 affiliateAmount = toAmount.mul(_affiliateFee).div(AFFILIATE_FEE_RESOLUTION);
                require(stepData.targetToken.transfer(_affiliateAccount, affiliateAmount), "ERR_FEE_TRANSFER_FAILED");
                toAmount -= affiliateAmount;
            }

            emit Conversion(stepData.anchor, stepData.sourceToken, stepData.targetToken, fromAmount, toAmount, msg.sender);
            fromAmount = toAmount;
        }

        // ensure the trade meets the minimum requested amount
        require(toAmount >= _minReturn, "ERR_RETURN_TOO_LOW");

        return toAmount;
    }

    /**
      * @dev validates msg.value and prepares the conversion source token for the conversion
      *
      * @param _sourceToken source token of the first conversion step
      * @param _anchor      converter anchor of the first conversion step
      * @param _amount      amount to convert from, in the source token
    */
    function handleSourceToken(IERC20Token _sourceToken, IConverterAnchor _anchor, uint256 _amount) private {
        IConverter firstConverter = IConverter(_anchor.owner());
        bool isNewerConverter = isV28OrHigherConverter(firstConverter);

        // ETH
        if (msg.value > 0) {
            // validate msg.value
            require(msg.value == _amount, "ERR_ETH_AMOUNT_MISMATCH");

            // EtherToken converter - deposit the ETH into the EtherToken
            // note that it can still be a non ETH converter if the path is wrong
            // but such conversion will simply revert
            if (!isNewerConverter)
                IEtherToken(getConverterEtherTokenAddress(firstConverter)).deposit.value(msg.value)();
        }
        // EtherToken
        else if (etherTokens[_sourceToken]) {
            // claim the tokens - if the source token is ETH reserve, this call will fail
            // since in that case the transaction must be sent with msg.value
            safeTransferFrom(_sourceToken, msg.sender, this, _amount);

            // ETH converter - withdraw the ETH
            if (isNewerConverter)
                IEtherToken(_sourceToken).withdraw(_amount);
        }
        // other ERC20 token
        else {
            // newer converter - transfer the tokens from the sender directly to the converter
            // otherwise claim the tokens
            if (isNewerConverter)
                safeTransferFrom(_sourceToken, msg.sender, firstConverter, _amount);
            else
                safeTransferFrom(_sourceToken, msg.sender, this, _amount);
        }
    }

    /**
      * @dev handles the conversion target token if the network still holds it at the end of the conversion
      *
      * @param _data        conversion data, see ConversionStep struct above
      * @param _amount      conversion return amount, in the target token
      * @param _beneficiary wallet to receive the conversion result
    */
    function handleTargetToken(ConversionStep[] _data, uint256 _amount, address _beneficiary) private {
        ConversionStep memory stepData = _data[_data.length - 1];

        // network contract doesn't hold the tokens, do nothing
        if (stepData.beneficiary != address(this))
            return;

        IERC20Token targetToken = stepData.targetToken;

        // ETH / EtherToken
        if (etherTokens[targetToken]) {
            // newer converter should send ETH directly to the beneficiary
            assert(!stepData.isV28OrHigherConverter);

            // EtherToken converter - withdraw the ETH and transfer to the beneficiary
            IEtherToken(targetToken).withdrawTo(_beneficiary, _amount);
        }
        // other ERC20 token
        else {
            safeTransfer(targetToken, _beneficiary, _amount);
        }
    }

    /**
      * @dev creates a memory cache of all conversion steps data to minimize logic and external calls during conversions
      *
      * @param _conversionPath      conversion path, see conversion path format above
      * @param _beneficiary         wallet to receive the conversion result
      * @param _affiliateFeeEnabled true if affiliate fee was requested by the sender, false if not
      *
      * @return cached conversion data to be ingested later on by the conversion flow
    */
    function createConversionData(IERC20Token[] _conversionPath, address _beneficiary, bool _affiliateFeeEnabled) private view returns (ConversionStep[]) {
        ConversionStep[] memory data = new ConversionStep[](_conversionPath.length / 2);

        bool affiliateFeeProcessed = false;
        address bntToken = addressOf(BNT_TOKEN);
        // iterate the conversion path and create the conversion data for each step
        uint256 i;
        for (i = 0; i < _conversionPath.length - 1; i += 2) {
            IConverterAnchor anchor = IConverterAnchor(_conversionPath[i + 1]);
            IConverter converter = IConverter(anchor.owner());
            IERC20Token targetToken = _conversionPath[i + 2];

            // check if the affiliate fee should be processed in this step
            bool processAffiliateFee = _affiliateFeeEnabled && !affiliateFeeProcessed && targetToken == bntToken;
            if (processAffiliateFee)
                affiliateFeeProcessed = true;

            data[i / 2] = ConversionStep({
                // set the converter anchor
                anchor: anchor,

                // set the converter
                converter: converter,

                // set the source/target tokens
                sourceToken: _conversionPath[i],
                targetToken: targetToken,

                // requires knowledge about the next step, so initialize in the next phase
                beneficiary: address(0),

                // set flags
                isV28OrHigherConverter: isV28OrHigherConverter(converter),
                processAffiliateFee: processAffiliateFee
            });
        }

        // ETH support
        // source is ETH
        ConversionStep memory stepData = data[0];
        if (etherTokens[stepData.sourceToken]) {
            // newer converter - replace the source token address with ETH reserve address
            if (stepData.isV28OrHigherConverter)
                stepData.sourceToken = IERC20Token(ETH_RESERVE_ADDRESS);
            // older converter - replace the source token with the EtherToken address used by the converter
            else
                stepData.sourceToken = IERC20Token(getConverterEtherTokenAddress(stepData.converter));
        }

        // target is ETH
        stepData = data[data.length - 1];
        if (etherTokens[stepData.targetToken]) {
            // newer converter - replace the target token address with ETH reserve address
            if (stepData.isV28OrHigherConverter)
                stepData.targetToken = IERC20Token(ETH_RESERVE_ADDRESS);
            // older converter - replace the target token with the EtherToken address used by the converter
            else
                stepData.targetToken = IERC20Token(getConverterEtherTokenAddress(stepData.converter));
        }

        // set the beneficiary for each step
        for (i = 0; i < data.length; i++) {
            stepData = data[i];

            // first check if the converter in this step is newer as older converters don't even support the beneficiary argument
            if (stepData.isV28OrHigherConverter) {
                // if affiliate fee is processed in this step, beneficiary is the network contract
                if (stepData.processAffiliateFee)
                    stepData.beneficiary = this;
                // if it's the last step, beneficiary is the final beneficiary
                else if (i == data.length - 1)
                    stepData.beneficiary = _beneficiary;
                // if the converter in the next step is newer, beneficiary is the next converter
                else if (data[i + 1].isV28OrHigherConverter)
                    stepData.beneficiary = data[i + 1].converter;
                // the converter in the next step is older, beneficiary is the network contract
                else
                    stepData.beneficiary = this;
            }
            else {
                // converter in this step is older, beneficiary is the network contract
                stepData.beneficiary = this;
            }
        }

        return data;
    }

    /**
      * @dev utility, checks whether allowance for the given spender exists and approves one if it doesn't.
      * Note that we use the non standard erc-20 interface in which `approve` has no return value so that
      * this function will work for both standard and non standard tokens
      *
      * @param _token   token to check the allowance in
      * @param _spender approved address
      * @param _value   allowance amount
    */
    function ensureAllowance(IERC20Token _token, address _spender, uint256 _value) private {
        uint256 allowance = _token.allowance(this, _spender);
        if (allowance < _value) {
            if (allowance > 0)
                safeApprove(_token, _spender, 0);
            safeApprove(_token, _spender, _value);
        }
    }

    // legacy - returns the address of an EtherToken used by the converter
    function getConverterEtherTokenAddress(IConverter _converter) private view returns (address) {
        uint256 reserveCount = _converter.connectorTokenCount();
        for (uint256 i = 0; i < reserveCount; i++) {
            address reserveTokenAddress = _converter.connectorTokens(i);
            if (etherTokens[reserveTokenAddress])
                return reserveTokenAddress;
        }

        return ETH_RESERVE_ADDRESS;
    }

    // legacy - if the token is an ether token, returns the ETH reserve address
    // used by the converter, otherwise returns the input token address
    function getConverterTokenAddress(IConverter _converter, IERC20Token _token) private view returns (IERC20Token) {
        if (!etherTokens[_token])
            return _token;

        if (isV28OrHigherConverter(_converter))
            return IERC20Token(ETH_RESERVE_ADDRESS);

        return IERC20Token(getConverterEtherTokenAddress(_converter));
    }

    bytes4 private constant GET_RETURN_FUNC_SELECTOR = bytes4(keccak256("getReturn(address,address,uint256)"));

    // using assembly code since older converter versions have different return values
    function getReturn(address _dest, address _sourceToken, address _targetToken, uint256 _amount) internal view returns (uint256, uint256) {
        uint256[2] memory ret;
        bytes memory data = abi.encodeWithSelector(GET_RETURN_FUNC_SELECTOR, _sourceToken, _targetToken, _amount);

        assembly {
            let success := staticcall(
                gas,           // gas remaining
                _dest,         // destination address
                add(data, 32), // input buffer (starts after the first 32 bytes in the `data` array)
                mload(data),   // input length (loaded from the first 32 bytes in the `data` array)
                ret,           // output buffer
                64             // output length
            )
            if iszero(success) {
                revert(0, 0)
            }
        }

        return (ret[0], ret[1]);
    }

    bytes4 private constant IS_V28_OR_HIGHER_FUNC_SELECTOR = bytes4(keccak256("isV28OrHigher()"));

    // using assembly code to identify converter version
    // can't rely on the version number since the function had a different signature in older converters
    function isV28OrHigherConverter(IConverter _converter) internal view returns (bool) {
        bool success;
        uint256[1] memory ret;
        bytes memory data = abi.encodeWithSelector(IS_V28_OR_HIGHER_FUNC_SELECTOR);

        assembly {
            success := staticcall(
                5000,          // isV28OrHigher consumes 190 gas, but just for extra safety
                _converter,    // destination address
                add(data, 32), // input buffer (starts after the first 32 bytes in the `data` array)
                mload(data),   // input length (loaded from the first 32 bytes in the `data` array)
                ret,           // output buffer
                32             // output length
            )
        }

        return success && ret[0] != 0;
    }

    /**
      * @dev deprecated, backward compatibility
    */
    function getReturnByPath(IERC20Token[] _path, uint256 _amount) public view returns (uint256, uint256) {
        return (rateByPath(_path, _amount), 0);
    }

    /**
      * @dev deprecated, backward compatibility
    */
    function convert(IERC20Token[] _path, uint256 _amount, uint256 _minReturn) public payable returns (uint256) {
        return convertByPath(_path, _amount, _minReturn, address(0), address(0), 0);
    }

    /**
      * @dev deprecated, backward compatibility
    */
    function convert2(
        IERC20Token[] _path,
        uint256 _amount,
        uint256 _minReturn,
        address _affiliateAccount,
        uint256 _affiliateFee
    )
        public
        payable
        returns (uint256)
    {
        return convertByPath(_path, _amount, _minReturn, address(0), _affiliateAccount, _affiliateFee);
    }

    /**
      * @dev deprecated, backward compatibility
    */
    function convertFor(IERC20Token[] _path, uint256 _amount, uint256 _minReturn, address _beneficiary) public payable returns (uint256) {
        return convertByPath(_path, _amount, _minReturn, _beneficiary, address(0), 0);
    }

    /**
      * @dev deprecated, backward compatibility
    */
    function convertFor2(
        IERC20Token[] _path,
        uint256 _amount,
        uint256 _minReturn,
        address _beneficiary,
        address _affiliateAccount,
        uint256 _affiliateFee
    )
        public
        payable
        greaterThanZero(_minReturn)
        returns (uint256)
    {
        return convertByPath(_path, _amount, _minReturn, _beneficiary, _affiliateAccount, _affiliateFee);
    }

    /**
      * @dev deprecated, backward compatibility
    */
    function claimAndConvert(IERC20Token[] _path, uint256 _amount, uint256 _minReturn) public returns (uint256) {
        return convertByPath(_path, _amount, _minReturn, address(0), address(0), 0);
    }

    /**
      * @dev deprecated, backward compatibility
    */
    function claimAndConvert2(
        IERC20Token[] _path,
        uint256 _amount,
        uint256 _minReturn,
        address _affiliateAccount,
        uint256 _affiliateFee
    )
        public
        returns (uint256)
    {
        return convertByPath(_path, _amount, _minReturn, address(0), _affiliateAccount, _affiliateFee);
    }

    /**
      * @dev deprecated, backward compatibility
    */
    function claimAndConvertFor(IERC20Token[] _path, uint256 _amount, uint256 _minReturn, address _beneficiary) public returns (uint256) {
        return convertByPath(_path, _amount, _minReturn, _beneficiary, address(0), 0);
    }

    /**
      * @dev deprecated, backward compatibility
    */
    function claimAndConvertFor2(
        IERC20Token[] _path,
        uint256 _amount,
        uint256 _minReturn,
        address _beneficiary,
        address _affiliateAccount,
        uint256 _affiliateFee
    )
        public
        returns (uint256)
    {
        return convertByPath(_path, _amount, _minReturn, _beneficiary, _affiliateAccount, _affiliateFee);
    }
}

pragma solidity ^0.4.11;

/*
    Overflow protected math functions
*/
contract SafeMath {
    /**
        constructor
    */
    function SafeMath() {
    }

    /**
        @dev returns the sum of _x and _y, asserts if the calculation overflows

        @param _x   value 1
        @param _y   value 2

        @return sum
    */
    function safeAdd(uint256 _x, uint256 _y) internal returns (uint256) {
        uint256 z = _x + _y;
        assert(z >= _x);
        return z;
    }

    /**
        @dev returns the difference of _x minus _y, asserts if the subtraction results in a negative number

        @param _x   minuend
        @param _y   subtrahend

        @return difference
    */
    function safeSub(uint256 _x, uint256 _y) internal returns (uint256) {
        assert(_x >= _y);
        return _x - _y;
    }

    /**
        @dev returns the product of multiplying _x by _y, asserts if the calculation overflows

        @param _x   factor 1
        @param _y   factor 2

        @return product
    */
    function safeMul(uint256 _x, uint256 _y) internal returns (uint256) {
        uint256 z = _x * _y;
        assert(_x == 0 || z / _x == _y);
        return z;
    }
} 

/*
    Owned contract interface
*/
contract IOwned {
    // this function isn't abstract since the compiler emits automatically generated getter functions as external
    function owner() public constant returns (address owner) { owner; }

    function transferOwnership(address _newOwner) public;
    function acceptOwnership() public;
}

/*
    Provides support and utilities for contract ownership
*/
contract Owned is IOwned {
    address public owner;
    address public newOwner;

    event OwnerUpdate(address _prevOwner, address _newOwner);

    /**
        @dev constructor
    */
    function Owned() {
        owner = msg.sender;
    }

    // allows execution by the owner only
    modifier ownerOnly {
        assert(msg.sender == owner);
        _;
    }

    /**
        @dev allows transferring the contract ownership
        the new owner still need to accept the transfer
        can only be called by the contract owner

        @param _newOwner    new contract owner
    */
    function transferOwnership(address _newOwner) public ownerOnly {
        require(_newOwner != owner);
        newOwner = _newOwner;
    }

    /**
        @dev used by a new owner to accept an ownership transfer
    */
    function acceptOwnership() public {
        require(msg.sender == newOwner);
        OwnerUpdate(owner, newOwner);
        owner = newOwner;
        newOwner = 0x0;
    }
}

/*
    Token Holder interface
*/
contract ITokenHolder is IOwned {
    function withdrawTokens(IERC20Token _token, address _to, uint256 _amount) public;
}

/*
    We consider every contract to be a 'token holder' since it's currently not possible
    for a contract to deny receiving tokens.

    The TokenHolder's contract sole purpose is to provide a safety mechanism that allows
    the owner to send tokens that were sent to the contract by mistake back to their sender.
*/
contract TokenHolder is ITokenHolder, Owned {
    /**
        @dev constructor
    */
    function TokenHolder() {
    }

    // validates an address - currently only checks that it isn't null
    modifier validAddress(address _address) {
        require(_address != 0x0);
        _;
    }

    // verifies that the address is different than this contract address
    modifier notThis(address _address) {
        require(_address != address(this));
        _;
    }

    /**
        @dev withdraws tokens held by the contract and sends them to an account
        can only be called by the owner

        @param _token   ERC20 token contract address
        @param _to      account to receive the new amount
        @param _amount  amount to withdraw
    */
    function withdrawTokens(IERC20Token _token, address _to, uint256 _amount)
        public
        ownerOnly
        validAddress(_token)
        validAddress(_to)
        notThis(_to)
    {
        assert(_token.transfer(_to, _amount));
    }
}

/*
    ERC20 Standard Token interface
*/
contract IERC20Token {
    // these functions aren't abstract since the compiler emits automatically generated getter functions as external
    function name() public constant returns (string name) { name; }
    function symbol() public constant returns (string symbol) { symbol; }
    function decimals() public constant returns (uint8 decimals) { decimals; }
    function totalSupply() public constant returns (uint256 totalSupply) { totalSupply; }
    function balanceOf(address _owner) public constant returns (uint256 balance) { _owner; balance; }
    function allowance(address _owner, address _spender) public constant returns (uint256 remaining) { _owner; _spender; remaining; }

    function transfer(address _to, uint256 _value) public returns (bool success);
    function transferFrom(address _from, address _to, uint256 _value) public returns (bool success);
    function approve(address _spender, uint256 _value) public returns (bool success);
}

/**
    ERC20 Standard Token implementation
*/
contract ERC20Token is IERC20Token, SafeMath {
    string public standard = 'Token 0.1';
    string public name = '';
    string public symbol = '';
    uint8 public decimals = 0;
    uint256 public totalSupply = 0;
    mapping (address => uint256) public balanceOf;
    mapping (address => mapping (address => uint256)) public allowance;

    event Transfer(address indexed _from, address indexed _to, uint256 _value);
    event Approval(address indexed _owner, address indexed _spender, uint256 _value);

    /**
        @dev constructor

        @param _name        token name
        @param _symbol      token symbol
        @param _decimals    decimal points, for display purposes
    */
    function ERC20Token(string _name, string _symbol, uint8 _decimals) {
        require(bytes(_name).length > 0 && bytes(_symbol).length > 0); // validate input

        name = _name;
        symbol = _symbol;
        decimals = _decimals;
    }

    // validates an address - currently only checks that it isn't null
    modifier validAddress(address _address) {
        require(_address != 0x0);
        _;
    }

    /**
        @dev send coins
        throws on any error rather then return a false flag to minimize user errors

        @param _to      target address
        @param _value   transfer amount

        @return true if the transfer was successful, false if it wasn't
    */
    function transfer(address _to, uint256 _value)
        public
        validAddress(_to)
        returns (bool success)
    {
        balanceOf[msg.sender] = safeSub(balanceOf[msg.sender], _value);
        balanceOf[_to] = safeAdd(balanceOf[_to], _value);
        Transfer(msg.sender, _to, _value);
        return true;
    }

    /**
        @dev an account/contract attempts to get the coins
        throws on any error rather then return a false flag to minimize user errors

        @param _from    source address
        @param _to      target address
        @param _value   transfer amount

        @return true if the transfer was successful, false if it wasn't
    */
    function transferFrom(address _from, address _to, uint256 _value)
        public
        validAddress(_from)
        validAddress(_to)
        returns (bool success)
    {
        allowance[_from][msg.sender] = safeSub(allowance[_from][msg.sender], _value);
        balanceOf[_from] = safeSub(balanceOf[_from], _value);
        balanceOf[_to] = safeAdd(balanceOf[_to], _value);
        Transfer(_from, _to, _value);
        return true;
    }

    /**
        @dev allow another account/contract to spend some tokens on your behalf
        throws on any error rather then return a false flag to minimize user errors

        also, to minimize the risk of the approve/transferFrom attack vector
        (see https://docs.google.com/document/d/1YLPtQxZu1UAvO9cZ1O2RPXBbT0mooh4DYKjA_jp-RLM/), approve has to be called twice
        in 2 separate transactions - once to change the allowance to 0 and secondly to change it to the new allowance value

        @param _spender approved address
        @param _value   allowance amount

        @return true if the approval was successful, false if it wasn't
    */
    function approve(address _spender, uint256 _value)
        public
        validAddress(_spender)
        returns (bool success)
    {
        // if the allowance isn't 0, it can only be updated to 0 to prevent an allowance change immediately after withdrawal
        require(_value == 0 || allowance[msg.sender][_spender] == 0);

        allowance[msg.sender][_spender] = _value;
        Approval(msg.sender, _spender, _value);
        return true;
    }
}

/*
    Smart Token interface
*/
contract ISmartToken is ITokenHolder, IERC20Token {
    function disableTransfers(bool _disable) public;
    function issue(address _to, uint256 _amount) public;
    function destroy(address _from, uint256 _amount) public;
}

/*
    Smart Token v0.2

    'Owned' is specified here for readability reasons
*/
contract SmartToken is ISmartToken, ERC20Token, Owned, TokenHolder {
    string public version = '0.2';

    bool public transfersEnabled = true;    // true if transfer/transferFrom are enabled, false if not

    // triggered when a smart token is deployed - the _token address is defined for forward compatibility, in case we want to trigger the event from a factory
    event NewSmartToken(address _token);
    // triggered when the total supply is increased
    event Issuance(uint256 _amount);
    // triggered when the total supply is decreased
    event Destruction(uint256 _amount);

    /**
        @dev constructor

        @param _name       token name
        @param _symbol     token short symbol, 1-6 characters
        @param _decimals   for display purposes only
    */
    function SmartToken(string _name, string _symbol, uint8 _decimals)
        ERC20Token(_name, _symbol, _decimals)
    {
        require(bytes(_symbol).length <= 6); // validate input
        NewSmartToken(address(this));
    }

    // allows execution only when transfers aren't disabled
    modifier transfersAllowed {
        assert(transfersEnabled);
        _;
    }

    /**
        @dev disables/enables transfers
        can only be called by the contract owner

        @param _disable    true to disable transfers, false to enable them
    */
    function disableTransfers(bool _disable) public ownerOnly {
        transfersEnabled = !_disable;
    }

    /**
        @dev increases the token supply and sends the new tokens to an account
        can only be called by the contract owner

        @param _to         account to receive the new amount
        @param _amount     amount to increase the supply by
    */
    function issue(address _to, uint256 _amount)
        public
        ownerOnly
        validAddress(_to)
        notThis(_to)
    {
        totalSupply = safeAdd(totalSupply, _amount);
        balanceOf[_to] = safeAdd(balanceOf[_to], _amount);

        Issuance(_amount);
        Transfer(this, _to, _amount);
    }

    /**
        @dev removes tokens from an account and decreases the token supply
        can only be called by the contract owner

        @param _from       account to remove the amount from
        @param _amount     amount to decrease the supply by
    */
    function destroy(address _from, uint256 _amount)
        public
        ownerOnly
    {
        balanceOf[_from] = safeSub(balanceOf[_from], _amount);
        totalSupply = safeSub(totalSupply, _amount);

        Transfer(_from, this, _amount);
        Destruction(_amount);
    }

    // ERC20 standard method overrides with some extra functionality

    /**
        @dev send coins
        throws on any error rather then return a false flag to minimize user errors
        note that when transferring to the smart token's address, the coins are actually destroyed

        @param _to      target address
        @param _value   transfer amount

        @return true if the transfer was successful, false if it wasn't
    */
    function transfer(address _to, uint256 _value) public transfersAllowed returns (bool success) {
        assert(super.transfer(_to, _value));

        // transferring to the contract address destroys tokens
        if (_to == address(this)) {
            balanceOf[_to] -= _value;
            totalSupply -= _value;
            Destruction(_value);
        }

        return true;
    }

    /**
        @dev an account/contract attempts to get the coins
        throws on any error rather then return a false flag to minimize user errors
        note that when transferring to the smart token's address, the coins are actually destroyed

        @param _from    source address
        @param _to      target address
        @param _value   transfer amount

        @return true if the transfer was successful, false if it wasn't
    */
    function transferFrom(address _from, address _to, uint256 _value) public transfersAllowed returns (bool success) {
        assert(super.transferFrom(_from, _to, _value));

        // transferring to the contract address destroys tokens
        if (_to == address(this)) {
            balanceOf[_to] -= _value;
            totalSupply -= _value;
            Destruction(_value);
        }

        return true;
    }
}

// Copyright (C) 2015, 2016, 2017 Dapphub

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

pragma solidity ^0.4.18;

contract WETH9 {
    string public name     = "Wrapped Ether";
    string public symbol   = "WETH";
    uint8  public decimals = 18;

    event  Approval(address indexed src, address indexed guy, uint wad);
    event  Transfer(address indexed src, address indexed dst, uint wad);
    event  Deposit(address indexed dst, uint wad);
    event  Withdrawal(address indexed src, uint wad);

    mapping (address => uint)                       public  balanceOf;
    mapping (address => mapping (address => uint))  public  allowance;

    function() public payable {
        deposit();
    }
    function deposit() public payable {
        balanceOf[msg.sender] += msg.value;
        Deposit(msg.sender, msg.value);
    }
    function withdraw(uint wad) public {
        require(balanceOf[msg.sender] >= wad);
        balanceOf[msg.sender] -= wad;
        msg.sender.transfer(wad);
        Withdrawal(msg.sender, wad);
    }

    function totalSupply() public view returns (uint) {
        return this.balance;
    }

    function approve(address guy, uint wad) public returns (bool) {
        allowance[msg.sender][guy] = wad;
        Approval(msg.sender, guy, wad);
        return true;
    }

    function transfer(address dst, uint wad) public returns (bool) {
        return transferFrom(msg.sender, dst, wad);
    }

    function transferFrom(address src, address dst, uint wad)
        public
        returns (bool)
    {
        require(balanceOf[src] >= wad);

        if (src != msg.sender && allowance[src][msg.sender] != uint(-1)) {
            require(allowance[src][msg.sender] >= wad);
            allowance[src][msg.sender] -= wad;
        }

        balanceOf[src] -= wad;
        balanceOf[dst] += wad;

        Transfer(src, dst, wad);

        return true;
    }
}


/*
                    GNU GENERAL PUBLIC LICENSE
                       Version 3, 29 June 2007

 Copyright (C) 2007 Free Software Foundation, Inc. <http://fsf.org/>
 Everyone is permitted to copy and distribute verbatim copies
 of this license document, but changing it is not allowed.

                            Preamble

  The GNU General Public License is a free, copyleft license for
software and other kinds of works.

  The licenses for most software and other practical works are designed
to take away your freedom to share and change the works.  By contrast,
the GNU General Public License is intended to guarantee your freedom to
share and change all versions of a program--to make sure it remains free
software for all its users.  We, the Free Software Foundation, use the
GNU General Public License for most of our software; it applies also to
any other work released this way by its authors.  You can apply it to
your programs, too.

  When we speak of free software, we are referring to freedom, not
price.  Our General Public Licenses are designed to make sure that you
have the freedom to distribute copies of free software (and charge for
them if you wish), that you receive source code or can get it if you
want it, that you can change the software or use pieces of it in new
free programs, and that you know you can do these things.

  To protect your rights, we need to prevent others from denying you
these rights or asking you to surrender the rights.  Therefore, you have
certain responsibilities if you distribute copies of the software, or if
you modify it: responsibilities to respect the freedom of others.

  For example, if you distribute copies of such a program, whether
gratis or for a fee, you must pass on to the recipients the same
freedoms that you received.  You must make sure that they, too, receive
or can get the source code.  And you must show them these terms so they
know their rights.

  Developers that use the GNU GPL protect your rights with two steps:
(1) assert copyright on the software, and (2) offer you this License
giving you legal permission to copy, distribute and/or modify it.

  For the developers' and authors' protection, the GPL clearly explains
that there is no warranty for this free software.  For both users' and
authors' sake, the GPL requires that modified versions be marked as
changed, so that their problems will not be attributed erroneously to
authors of previous versions.

  Some devices are designed to deny users access to install or run
modified versions of the software inside them, although the manufacturer
can do so.  This is fundamentally incompatible with the aim of
protecting users' freedom to change the software.  The systematic
pattern of such abuse occurs in the area of products for individuals to
use, which is precisely where it is most unacceptable.  Therefore, we
have designed this version of the GPL to prohibit the practice for those
products.  If such problems arise substantially in other domains, we
stand ready to extend this provision to those domains in future versions
of the GPL, as needed to protect the freedom of users.

  Finally, every program is threatened constantly by software patents.
States should not allow patents to restrict development and use of
software on general-purpose computers, but in those that do, we wish to
avoid the special danger that patents applied to a free program could
make it effectively proprietary.  To prevent this, the GPL assures that
patents cannot be used to render the program non-free.

  The precise terms and conditions for copying, distribution and
modification follow.

                       TERMS AND CONDITIONS

  0. Definitions.

  "This License" refers to version 3 of the GNU General Public License.

  "Copyright" also means copyright-like laws that apply to other kinds of
works, such as semiconductor masks.

  "The Program" refers to any copyrightable work licensed under this
License.  Each licensee is addressed as "you".  "Licensees" and
"recipients" may be individuals or organizations.

  To "modify" a work means to copy from or adapt all or part of the work
in a fashion requiring copyright permission, other than the making of an
exact copy.  The resulting work is called a "modified version" of the
earlier work or a work "based on" the earlier work.

  A "covered work" means either the unmodified Program or a work based
on the Program.

  To "propagate" a work means to do anything with it that, without
permission, would make you directly or secondarily liable for
infringement under applicable copyright law, except executing it on a
computer or modifying a private copy.  Propagation includes copying,
distribution (with or without modification), making available to the
public, and in some countries other activities as well.

  To "convey" a work means any kind of propagation that enables other
parties to make or receive copies.  Mere interaction with a user through
a computer network, with no transfer of a copy, is not conveying.

  An interactive user interface displays "Appropriate Legal Notices"
to the extent that it includes a convenient and prominently visible
feature that (1) displays an appropriate copyright notice, and (2)
tells the user that there is no warranty for the work (except to the
extent that warranties are provided), that licensees may convey the
work under this License, and how to view a copy of this License.  If
the interface presents a list of user commands or options, such as a
menu, a prominent item in the list meets this criterion.

  1. Source Code.

  The "source code" for a work means the preferred form of the work
for making modifications to it.  "Object code" means any non-source
form of a work.

  A "Standard Interface" means an interface that either is an official
standard defined by a recognized standards body, or, in the case of
interfaces specified for a particular programming language, one that
is widely used among developers working in that language.

  The "System Libraries" of an executable work include anything, other
than the work as a whole, that (a) is included in the normal form of
packaging a Major Component, but which is not part of that Major
Component, and (b) serves only to enable use of the work with that
Major Component, or to implement a Standard Interface for which an
implementation is available to the public in source code form.  A
"Major Component", in this context, means a major essential component
(kernel, window system, and so on) of the specific operating system
(if any) on which the executable work runs, or a compiler used to
produce the work, or an object code interpreter used to run it.

  The "Corresponding Source" for a work in object code form means all
the source code needed to generate, install, and (for an executable
work) run the object code and to modify the work, including scripts to
control those activities.  However, it does not include the work's
System Libraries, or general-purpose tools or generally available free
programs which are used unmodified in performing those activities but
which are not part of the work.  For example, Corresponding Source
includes interface definition files associated with source files for
the work, and the source code for shared libraries and dynamically
linked subprograms that the work is specifically designed to require,
such as by intimate data communication or control flow between those
subprograms and other parts of the work.

  The Corresponding Source need not include anything that users
can regenerate automatically from other parts of the Corresponding
Source.

  The Corresponding Source for a work in source code form is that
same work.

  2. Basic Permissions.

  All rights granted under this License are granted for the term of
copyright on the Program, and are irrevocable provided the stated
conditions are met.  This License explicitly affirms your unlimited
permission to run the unmodified Program.  The output from running a
covered work is covered by this License only if the output, given its
content, constitutes a covered work.  This License acknowledges your
rights of fair use or other equivalent, as provided by copyright law.

  You may make, run and propagate covered works that you do not
convey, without conditions so long as your license otherwise remains
in force.  You may convey covered works to others for the sole purpose
of having them make modifications exclusively for you, or provide you
with facilities for running those works, provided that you comply with
the terms of this License in conveying all material for which you do
not control copyright.  Those thus making or running the covered works
for you must do so exclusively on your behalf, under your direction
and control, on terms that prohibit them from making any copies of
your copyrighted material outside their relationship with you.

  Conveying under any other circumstances is permitted solely under
the conditions stated below.  Sublicensing is not allowed; section 10
makes it unnecessary.

  3. Protecting Users' Legal Rights From Anti-Circumvention Law.

  No covered work shall be deemed part of an effective technological
measure under any applicable law fulfilling obligations under article
11 of the WIPO copyright treaty adopted on 20 December 1996, or
similar laws prohibiting or restricting circumvention of such
measures.

  When you convey a covered work, you waive any legal power to forbid
circumvention of technological measures to the extent such circumvention
is effected by exercising rights under this License with respect to
the covered work, and you disclaim any intention to limit operation or
modification of the work as a means of enforcing, against the work's
users, your or third parties' legal rights to forbid circumvention of
technological measures.

  4. Conveying Verbatim Copies.

  You may convey verbatim copies of the Program's source code as you
receive it, in any medium, provided that you conspicuously and
appropriately publish on each copy an appropriate copyright notice;
keep intact all notices stating that this License and any
non-permissive terms added in accord with section 7 apply to the code;
keep intact all notices of the absence of any warranty; and give all
recipients a copy of this License along with the Program.

  You may charge any price or no price for each copy that you convey,
and you may offer support or warranty protection for a fee.

  5. Conveying Modified Source Versions.

  You may convey a work based on the Program, or the modifications to
produce it from the Program, in the form of source code under the
terms of section 4, provided that you also meet all of these conditions:

    a) The work must carry prominent notices stating that you modified
    it, and giving a relevant date.

    b) The work must carry prominent notices stating that it is
    released under this License and any conditions added under section
    7.  This requirement modifies the requirement in section 4 to
    "keep intact all notices".

    c) You must license the entire work, as a whole, under this
    License to anyone who comes into possession of a copy.  This
    License will therefore apply, along with any applicable section 7
    additional terms, to the whole of the work, and all its parts,
    regardless of how they are packaged.  This License gives no
    permission to license the work in any other way, but it does not
    invalidate such permission if you have separately received it.

    d) If the work has interactive user interfaces, each must display
    Appropriate Legal Notices; however, if the Program has interactive
    interfaces that do not display Appropriate Legal Notices, your
    work need not make them do so.

  A compilation of a covered work with other separate and independent
works, which are not by their nature extensions of the covered work,
and which are not combined with it such as to form a larger program,
in or on a volume of a storage or distribution medium, is called an
"aggregate" if the compilation and its resulting copyright are not
used to limit the access or legal rights of the compilation's users
beyond what the individual works permit.  Inclusion of a covered work
in an aggregate does not cause this License to apply to the other
parts of the aggregate.

  6. Conveying Non-Source Forms.

  You may convey a covered work in object code form under the terms
of sections 4 and 5, provided that you also convey the
machine-readable Corresponding Source under the terms of this License,
in one of these ways:

    a) Convey the object code in, or embodied in, a physical product
    (including a physical distribution medium), accompanied by the
    Corresponding Source fixed on a durable physical medium
    customarily used for software interchange.

    b) Convey the object code in, or embodied in, a physical product
    (including a physical distribution medium), accompanied by a
    written offer, valid for at least three years and valid for as
    long as you offer spare parts or customer support for that product
    model, to give anyone who possesses the object code either (1) a
    copy of the Corresponding Source for all the software in the
    product that is covered by this License, on a durable physical
    medium customarily used for software interchange, for a price no
    more than your reasonable cost of physically performing this
    conveying of source, or (2) access to copy the
    Corresponding Source from a network server at no charge.

    c) Convey individual copies of the object code with a copy of the
    written offer to provide the Corresponding Source.  This
    alternative is allowed only occasionally and noncommercially, and
    only if you received the object code with such an offer, in accord
    with subsection 6b.

    d) Convey the object code by offering access from a designated
    place (gratis or for a charge), and offer equivalent access to the
    Corresponding Source in the same way through the same place at no
    further charge.  You need not require recipients to copy the
    Corresponding Source along with the object code.  If the place to
    copy the object code is a network server, the Corresponding Source
    may be on a different server (operated by you or a third party)
    that supports equivalent copying facilities, provided you maintain
    clear directions next to the object code saying where to find the
    Corresponding Source.  Regardless of what server hosts the
    Corresponding Source, you remain obligated to ensure that it is
    available for as long as needed to satisfy these requirements.

    e) Convey the object code using peer-to-peer transmission, provided
    you inform other peers where the object code and Corresponding
    Source of the work are being offered to the general public at no
    charge under subsection 6d.

  A separable portion of the object code, whose source code is excluded
from the Corresponding Source as a System Library, need not be
included in conveying the object code work.

  A "User Product" is either (1) a "consumer product", which means any
tangible personal property which is normally used for personal, family,
or household purposes, or (2) anything designed or sold for incorporation
into a dwelling.  In determining whether a product is a consumer product,
doubtful cases shall be resolved in favor of coverage.  For a particular
product received by a particular user, "normally used" refers to a
typical or common use of that class of product, regardless of the status
of the particular user or of the way in which the particular user
actually uses, or expects or is expected to use, the product.  A product
is a consumer product regardless of whether the product has substantial
commercial, industrial or non-consumer uses, unless such uses represent
the only significant mode of use of the product.

  "Installation Information" for a User Product means any methods,
procedures, authorization keys, or other information required to install
and execute modified versions of a covered work in that User Product from
a modified version of its Corresponding Source.  The information must
suffice to ensure that the continued functioning of the modified object
code is in no case prevented or interfered with solely because
modification has been made.

  If you convey an object code work under this section in, or with, or
specifically for use in, a User Product, and the conveying occurs as
part of a transaction in which the right of possession and use of the
User Product is transferred to the recipient in perpetuity or for a
fixed term (regardless of how the transaction is characterized), the
Corresponding Source conveyed under this section must be accompanied
by the Installation Information.  But this requirement does not apply
if neither you nor any third party retains the ability to install
modified object code on the User Product (for example, the work has
been installed in ROM).

  The requirement to provide Installation Information does not include a
requirement to continue to provide support service, warranty, or updates
for a work that has been modified or installed by the recipient, or for
the User Product in which it has been modified or installed.  Access to a
network may be denied when the modification itself materially and
adversely affects the operation of the network or violates the rules and
protocols for communication across the network.

  Corresponding Source conveyed, and Installation Information provided,
in accord with this section must be in a format that is publicly
documented (and with an implementation available to the public in
source code form), and must require no special password or key for
unpacking, reading or copying.

  7. Additional Terms.

  "Additional permissions" are terms that supplement the terms of this
License by making exceptions from one or more of its conditions.
Additional permissions that are applicable to the entire Program shall
be treated as though they were included in this License, to the extent
that they are valid under applicable law.  If additional permissions
apply only to part of the Program, that part may be used separately
under those permissions, but the entire Program remains governed by
this License without regard to the additional permissions.

  When you convey a copy of a covered work, you may at your option
remove any additional permissions from that copy, or from any part of
it.  (Additional permissions may be written to require their own
removal in certain cases when you modify the work.)  You may place
additional permissions on material, added by you to a covered work,
for which you have or can give appropriate copyright permission.

  Notwithstanding any other provision of this License, for material you
add to a covered work, you may (if authorized by the copyright holders of
that material) supplement the terms of this License with terms:

    a) Disclaiming warranty or limiting liability differently from the
    terms of sections 15 and 16 of this License; or

    b) Requiring preservation of specified reasonable legal notices or
    author attributions in that material or in the Appropriate Legal
    Notices displayed by works containing it; or

    c) Prohibiting misrepresentation of the origin of that material, or
    requiring that modified versions of such material be marked in
    reasonable ways as different from the original version; or

    d) Limiting the use for publicity purposes of names of licensors or
    authors of the material; or

    e) Declining to grant rights under trademark law for use of some
    trade names, trademarks, or service marks; or

    f) Requiring indemnification of licensors and authors of that
    material by anyone who conveys the material (or modified versions of
    it) with contractual assumptions of liability to the recipient, for
    any liability that these contractual assumptions directly impose on
    those licensors and authors.

  All other non-permissive additional terms are considered "further
restrictions" within the meaning of section 10.  If the Program as you
received it, or any part of it, contains a notice stating that it is
governed by this License along with a term that is a further
restriction, you may remove that term.  If a license document contains
a further restriction but permits relicensing or conveying under this
License, you may add to a covered work material governed by the terms
of that license document, provided that the further restriction does
not survive such relicensing or conveying.

  If you add terms to a covered work in accord with this section, you
must place, in the relevant source files, a statement of the
additional terms that apply to those files, or a notice indicating
where to find the applicable terms.

  Additional terms, permissive or non-permissive, may be stated in the
form of a separately written license, or stated as exceptions;
the above requirements apply either way.

  8. Termination.

  You may not propagate or modify a covered work except as expressly
provided under this License.  Any attempt otherwise to propagate or
modify it is void, and will automatically terminate your rights under
this License (including any patent licenses granted under the third
paragraph of section 11).

  However, if you cease all violation of this License, then your
license from a particular copyright holder is reinstated (a)
provisionally, unless and until the copyright holder explicitly and
finally terminates your license, and (b) permanently, if the copyright
holder fails to notify you of the violation by some reasonable means
prior to 60 days after the cessation.

  Moreover, your license from a particular copyright holder is
reinstated permanently if the copyright holder notifies you of the
violation by some reasonable means, this is the first time you have
received notice of violation of this License (for any work) from that
copyright holder, and you cure the violation prior to 30 days after
your receipt of the notice.

  Termination of your rights under this section does not terminate the
licenses of parties who have received copies or rights from you under
this License.  If your rights have been terminated and not permanently
reinstated, you do not qualify to receive new licenses for the same
material under section 10.

  9. Acceptance Not Required for Having Copies.

  You are not required to accept this License in order to receive or
run a copy of the Program.  Ancillary propagation of a covered work
occurring solely as a consequence of using peer-to-peer transmission
to receive a copy likewise does not require acceptance.  However,
nothing other than this License grants you permission to propagate or
modify any covered work.  These actions infringe copyright if you do
not accept this License.  Therefore, by modifying or propagating a
covered work, you indicate your acceptance of this License to do so.

  10. Automatic Licensing of Downstream Recipients.

  Each time you convey a covered work, the recipient automatically
receives a license from the original licensors, to run, modify and
propagate that work, subject to this License.  You are not responsible
for enforcing compliance by third parties with this License.

  An "entity transaction" is a transaction transferring control of an
organization, or substantially all assets of one, or subdividing an
organization, or merging organizations.  If propagation of a covered
work results from an entity transaction, each party to that
transaction who receives a copy of the work also receives whatever
licenses to the work the party's predecessor in interest had or could
give under the previous paragraph, plus a right to possession of the
Corresponding Source of the work from the predecessor in interest, if
the predecessor has it or can get it with reasonable efforts.

  You may not impose any further restrictions on the exercise of the
rights granted or affirmed under this License.  For example, you may
not impose a license fee, royalty, or other charge for exercise of
rights granted under this License, and you may not initiate litigation
(including a cross-claim or counterclaim in a lawsuit) alleging that
any patent claim is infringed by making, using, selling, offering for
sale, or importing the Program or any portion of it.

  11. Patents.

  A "contributor" is a copyright holder who authorizes use under this
License of the Program or a work on which the Program is based.  The
work thus licensed is called the contributor's "contributor version".

  A contributor's "essential patent claims" are all patent claims
owned or controlled by the contributor, whether already acquired or
hereafter acquired, that would be infringed by some manner, permitted
by this License, of making, using, or selling its contributor version,
but do not include claims that would be infringed only as a
consequence of further modification of the contributor version.  For
purposes of this definition, "control" includes the right to grant
patent sublicenses in a manner consistent with the requirements of
this License.

  Each contributor grants you a non-exclusive, worldwide, royalty-free
patent license under the contributor's essential patent claims, to
make, use, sell, offer for sale, import and otherwise run, modify and
propagate the contents of its contributor version.

  In the following three paragraphs, a "patent license" is any express
agreement or commitment, however denominated, not to enforce a patent
(such as an express permission to practice a patent or covenant not to
sue for patent infringement).  To "grant" such a patent license to a
party means to make such an agreement or commitment not to enforce a
patent against the party.

  If you convey a covered work, knowingly relying on a patent license,
and the Corresponding Source of the work is not available for anyone
to copy, free of charge and under the terms of this License, through a
publicly available network server or other readily accessible means,
then you must either (1) cause the Corresponding Source to be so
available, or (2) arrange to deprive yourself of the benefit of the
patent license for this particular work, or (3) arrange, in a manner
consistent with the requirements of this License, to extend the patent
license to downstream recipients.  "Knowingly relying" means you have
actual knowledge that, but for the patent license, your conveying the
covered work in a country, or your recipient's use of the covered work
in a country, would infringe one or more identifiable patents in that
country that you have reason to believe are valid.

  If, pursuant to or in connection with a single transaction or
arrangement, you convey, or propagate by procuring conveyance of, a
covered work, and grant a patent license to some of the parties
receiving the covered work authorizing them to use, propagate, modify
or convey a specific copy of the covered work, then the patent license
you grant is automatically extended to all recipients of the covered
work and works based on it.

  A patent license is "discriminatory" if it does not include within
the scope of its coverage, prohibits the exercise of, or is
conditioned on the non-exercise of one or more of the rights that are
specifically granted under this License.  You may not convey a covered
work if you are a party to an arrangement with a third party that is
in the business of distributing software, under which you make payment
to the third party based on the extent of your activity of conveying
the work, and under which the third party grants, to any of the
parties who would receive the covered work from you, a discriminatory
patent license (a) in connection with copies of the covered work
conveyed by you (or copies made from those copies), or (b) primarily
for and in connection with specific products or compilations that
contain the covered work, unless you entered into that arrangement,
or that patent license was granted, prior to 28 March 2007.

  Nothing in this License shall be construed as excluding or limiting
any implied license or other defenses to infringement that may
otherwise be available to you under applicable patent law.

  12. No Surrender of Others' Freedom.

  If conditions are imposed on you (whether by court order, agreement or
otherwise) that contradict the conditions of this License, they do not
excuse you from the conditions of this License.  If you cannot convey a
covered work so as to satisfy simultaneously your obligations under this
License and any other pertinent obligations, then as a consequence you may
not convey it at all.  For example, if you agree to terms that obligate you
to collect a royalty for further conveying from those to whom you convey
the Program, the only way you could satisfy both those terms and this
License would be to refrain entirely from conveying the Program.

  13. Use with the GNU Affero General Public License.

  Notwithstanding any other provision of this License, you have
permission to link or combine any covered work with a work licensed
under version 3 of the GNU Affero General Public License into a single
combined work, and to convey the resulting work.  The terms of this
License will continue to apply to the part which is the covered work,
but the special requirements of the GNU Affero General Public License,
section 13, concerning interaction through a network will apply to the
combination as such.

  14. Revised Versions of this License.

  The Free Software Foundation may publish revised and/or new versions of
the GNU General Public License from time to time.  Such new versions will
be similar in spirit to the present version, but may differ in detail to
address new problems or concerns.

  Each version is given a distinguishing version number.  If the
Program specifies that a certain numbered version of the GNU General
Public License "or any later version" applies to it, you have the
option of following the terms and conditions either of that numbered
version or of any later version published by the Free Software
Foundation.  If the Program does not specify a version number of the
GNU General Public License, you may choose any version ever published
by the Free Software Foundation.

  If the Program specifies that a proxy can decide which future
versions of the GNU General Public License can be used, that proxy's
public statement of acceptance of a version permanently authorizes you
to choose that version for the Program.

  Later license versions may give you additional or different
permissions.  However, no additional obligations are imposed on any
author or copyright holder as a result of your choosing to follow a
later version.

  15. Disclaimer of Warranty.

  THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
APPLICABLE LAW.  EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY
OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO,
THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
PURPOSE.  THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM
IS WITH YOU.  SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF
ALL NECESSARY SERVICING, REPAIR OR CORRECTION.

  16. Limitation of Liability.

  IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
SUCH DAMAGES.

  17. Interpretation of Sections 15 and 16.

  If the disclaimer of warranty and limitation of liability provided
above cannot be given local legal effect according to their terms,
reviewing courts shall apply local law that most closely approximates
an absolute waiver of all civil liability in connection with the
Program, unless a warranty or assumption of liability accompanies a
copy of the Program in return for a fee.

                     END OF TERMS AND CONDITIONS

            How to Apply These Terms to Your New Programs

  If you develop a new program, and you want it to be of the greatest
possible use to the public, the best way to achieve this is to make it
free software which everyone can redistribute and change under these terms.

  To do so, attach the following notices to the program.  It is safest
to attach them to the start of each source file to most effectively
state the exclusion of warranty; and each file should have at least
the "copyright" line and a pointer to where the full notice is found.

    <one line to give the program's name and a brief idea of what it does.>
    Copyright (C) <year>  <name of author>

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.

Also add information on how to contact you by electronic and paper mail.

  If the program does terminal interaction, make it output a short
notice like this when it starts in an interactive mode:

    <program>  Copyright (C) <year>  <name of author>
    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
    This is free software, and you are welcome to redistribute it
    under certain conditions; type `show c' for details.

The hypothetical commands `show w' and `show c' should show the appropriate
parts of the General Public License.  Of course, your program's commands
might be different; for a GUI interface, you would use an "about box".

  You should also get your employer (if you work as a programmer) or school,
if any, to sign a "copyright disclaimer" for the program, if necessary.
For more information on this, and how to apply and follow the GNU GPL, see
<http://www.gnu.org/licenses/>.

  The GNU General Public License does not permit incorporating your program
into proprietary programs.  If your program is a subroutine library, you
may consider it more useful to permit linking proprietary applications with
the library.  If this is what you want to do, use the GNU Lesser General
Public License instead of this License.  But first, please read
<http://www.gnu.org/philosophy/why-not-lgpl.html>.

*/