// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (access/Ownable.sol)
pragma solidity ^0.8.0;
import "../utils/Context.sol";
/**
 * @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() {
        _transferOwnership(_msgSender());
    }
    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        _checkOwner();
        _;
    }
    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }
    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        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 {
        _transferOwnership(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");
        _transferOwnership(newOwner);
    }
    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (interfaces/draft-IERC1822.sol)
pragma solidity ^0.8.0;
/**
 * @dev ERC1822: Universal Upgradeable Proxy Standard (UUPS) documents a method for upgradeability through a simplified
 * proxy whose upgrades are fully controlled by the current implementation.
 */
interface IERC1822Proxiable {
    /**
     * @dev Returns the storage slot that the proxiable contract assumes is being used to store the implementation
     * address.
     *
     * IMPORTANT: A proxy pointing at a proxiable contract should not be considered proxiable itself, because this risks
     * bricking a proxy that upgrades to it, by delegating to itself until out of gas. Thus it is critical that this
     * function revert if invoked through a proxy.
     */
    function proxiableUUID() external view returns (bytes32);
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.3) (interfaces/IERC1967.sol)
pragma solidity ^0.8.0;
/**
 * @dev ERC-1967: Proxy Storage Slots. This interface contains the events defined in the ERC.
 *
 * _Available since v4.9._
 */
interface IERC1967 {
    /**
     * @dev Emitted when the implementation is upgraded.
     */
    event Upgraded(address indexed implementation);
    /**
     * @dev Emitted when the admin account has changed.
     */
    event AdminChanged(address previousAdmin, address newAdmin);
    /**
     * @dev Emitted when the beacon is changed.
     */
    event BeaconUpgraded(address indexed beacon);
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (proxy/beacon/BeaconProxy.sol)
pragma solidity ^0.8.0;
import "./IBeacon.sol";
import "../Proxy.sol";
import "../ERC1967/ERC1967Upgrade.sol";
/**
 * @dev This contract implements a proxy that gets the implementation address for each call from an {UpgradeableBeacon}.
 *
 * The beacon address is stored in storage slot `uint256(keccak256('eip1967.proxy.beacon')) - 1`, so that it doesn't
 * conflict with the storage layout of the implementation behind the proxy.
 *
 * _Available since v3.4._
 */
contract BeaconProxy is Proxy, ERC1967Upgrade {
    /**
     * @dev Initializes the proxy with `beacon`.
     *
     * If `data` is nonempty, it's used as data in a delegate call to the implementation returned by the beacon. This
     * will typically be an encoded function call, and allows initializing the storage of the proxy like a Solidity
     * constructor.
     *
     * Requirements:
     *
     * - `beacon` must be a contract with the interface {IBeacon}.
     */
    constructor(address beacon, bytes memory data) payable {
        _upgradeBeaconToAndCall(beacon, data, false);
    }
    /**
     * @dev Returns the current beacon address.
     */
    function _beacon() internal view virtual returns (address) {
        return _getBeacon();
    }
    /**
     * @dev Returns the current implementation address of the associated beacon.
     */
    function _implementation() internal view virtual override returns (address) {
        return IBeacon(_getBeacon()).implementation();
    }
    /**
     * @dev Changes the proxy to use a new beacon. Deprecated: see {_upgradeBeaconToAndCall}.
     *
     * If `data` is nonempty, it's used as data in a delegate call to the implementation returned by the beacon.
     *
     * Requirements:
     *
     * - `beacon` must be a contract.
     * - The implementation returned by `beacon` must be a contract.
     */
    function _setBeacon(address beacon, bytes memory data) internal virtual {
        _upgradeBeaconToAndCall(beacon, data, false);
    }
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (proxy/beacon/IBeacon.sol)
pragma solidity ^0.8.0;
/**
 * @dev This is the interface that {BeaconProxy} expects of its beacon.
 */
interface IBeacon {
    /**
     * @dev Must return an address that can be used as a delegate call target.
     *
     * {BeaconProxy} will check that this address is a contract.
     */
    function implementation() external view returns (address);
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (proxy/beacon/UpgradeableBeacon.sol)
pragma solidity ^0.8.0;
import "./IBeacon.sol";
import "../../access/Ownable.sol";
import "../../utils/Address.sol";
/**
 * @dev This contract is used in conjunction with one or more instances of {BeaconProxy} to determine their
 * implementation contract, which is where they will delegate all function calls.
 *
 * An owner is able to change the implementation the beacon points to, thus upgrading the proxies that use this beacon.
 */
contract UpgradeableBeacon is IBeacon, Ownable {
    address private _implementation;
    /**
     * @dev Emitted when the implementation returned by the beacon is changed.
     */
    event Upgraded(address indexed implementation);
    /**
     * @dev Sets the address of the initial implementation, and the deployer account as the owner who can upgrade the
     * beacon.
     */
    constructor(address implementation_) {
        _setImplementation(implementation_);
    }
    /**
     * @dev Returns the current implementation address.
     */
    function implementation() public view virtual override returns (address) {
        return _implementation;
    }
    /**
     * @dev Upgrades the beacon to a new implementation.
     *
     * Emits an {Upgraded} event.
     *
     * Requirements:
     *
     * - msg.sender must be the owner of the contract.
     * - `newImplementation` must be a contract.
     */
    function upgradeTo(address newImplementation) public virtual onlyOwner {
        _setImplementation(newImplementation);
        emit Upgraded(newImplementation);
    }
    /**
     * @dev Sets the implementation contract address for this beacon
     *
     * Requirements:
     *
     * - `newImplementation` must be a contract.
     */
    function _setImplementation(address newImplementation) private {
        require(Address.isContract(newImplementation), "UpgradeableBeacon: implementation is not a contract");
        _implementation = newImplementation;
    }
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (proxy/ERC1967/ERC1967Proxy.sol)
pragma solidity ^0.8.0;
import "../Proxy.sol";
import "./ERC1967Upgrade.sol";
/**
 * @dev This contract implements an upgradeable proxy. It is upgradeable because calls are delegated to an
 * implementation address that can be changed. This address is stored in storage in the location specified by
 * https://eips.ethereum.org/EIPS/eip-1967[EIP1967], so that it doesn't conflict with the storage layout of the
 * implementation behind the proxy.
 */
contract ERC1967Proxy is Proxy, ERC1967Upgrade {
    /**
     * @dev Initializes the upgradeable proxy with an initial implementation specified by `_logic`.
     *
     * If `_data` is nonempty, it's used as data in a delegate call to `_logic`. This will typically be an encoded
     * function call, and allows initializing the storage of the proxy like a Solidity constructor.
     */
    constructor(address _logic, bytes memory _data) payable {
        _upgradeToAndCall(_logic, _data, false);
    }
    /**
     * @dev Returns the current implementation address.
     */
    function _implementation() internal view virtual override returns (address impl) {
        return ERC1967Upgrade._getImplementation();
    }
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.3) (proxy/ERC1967/ERC1967Upgrade.sol)
pragma solidity ^0.8.2;
import "../beacon/IBeacon.sol";
import "../../interfaces/IERC1967.sol";
import "../../interfaces/draft-IERC1822.sol";
import "../../utils/Address.sol";
import "../../utils/StorageSlot.sol";
/**
 * @dev This abstract contract provides getters and event emitting update functions for
 * https://eips.ethereum.org/EIPS/eip-1967[EIP1967] slots.
 *
 * _Available since v4.1._
 *
 * @custom:oz-upgrades-unsafe-allow delegatecall
 */
abstract contract ERC1967Upgrade is IERC1967 {
    // This is the keccak-256 hash of "eip1967.proxy.rollback" subtracted by 1
    bytes32 private constant _ROLLBACK_SLOT = 0x4910fdfa16fed3260ed0e7147f7cc6da11a60208b5b9406d12a635614ffd9143;
    /**
     * @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 address.
     */
    function _getImplementation() internal view returns (address) {
        return StorageSlot.getAddressSlot(_IMPLEMENTATION_SLOT).value;
    }
    /**
     * @dev Stores a new address in the EIP1967 implementation slot.
     */
    function _setImplementation(address newImplementation) private {
        require(Address.isContract(newImplementation), "ERC1967: new implementation is not a contract");
        StorageSlot.getAddressSlot(_IMPLEMENTATION_SLOT).value = newImplementation;
    }
    /**
     * @dev Perform implementation upgrade
     *
     * Emits an {Upgraded} event.
     */
    function _upgradeTo(address newImplementation) internal {
        _setImplementation(newImplementation);
        emit Upgraded(newImplementation);
    }
    /**
     * @dev Perform implementation upgrade with additional setup call.
     *
     * Emits an {Upgraded} event.
     */
    function _upgradeToAndCall(
        address newImplementation,
        bytes memory data,
        bool forceCall
    ) internal {
        _upgradeTo(newImplementation);
        if (data.length > 0 || forceCall) {
            Address.functionDelegateCall(newImplementation, data);
        }
    }
    /**
     * @dev Perform implementation upgrade with security checks for UUPS proxies, and additional setup call.
     *
     * Emits an {Upgraded} event.
     */
    function _upgradeToAndCallUUPS(
        address newImplementation,
        bytes memory data,
        bool forceCall
    ) internal {
        // Upgrades from old implementations will perform a rollback test. This test requires the new
        // implementation to upgrade back to the old, non-ERC1822 compliant, implementation. Removing
        // this special case will break upgrade paths from old UUPS implementation to new ones.
        if (StorageSlot.getBooleanSlot(_ROLLBACK_SLOT).value) {
            _setImplementation(newImplementation);
        } else {
            try IERC1822Proxiable(newImplementation).proxiableUUID() returns (bytes32 slot) {
                require(slot == _IMPLEMENTATION_SLOT, "ERC1967Upgrade: unsupported proxiableUUID");
            } catch {
                revert("ERC1967Upgrade: new implementation is not UUPS");
            }
            _upgradeToAndCall(newImplementation, data, forceCall);
        }
    }
    /**
     * @dev Storage slot with the admin of the contract.
     * This is the keccak-256 hash of "eip1967.proxy.admin" subtracted by 1, and is
     * validated in the constructor.
     */
    bytes32 internal constant _ADMIN_SLOT = 0xb53127684a568b3173ae13b9f8a6016e243e63b6e8ee1178d6a717850b5d6103;
    /**
     * @dev Returns the current admin.
     */
    function _getAdmin() internal view returns (address) {
        return StorageSlot.getAddressSlot(_ADMIN_SLOT).value;
    }
    /**
     * @dev Stores a new address in the EIP1967 admin slot.
     */
    function _setAdmin(address newAdmin) private {
        require(newAdmin != address(0), "ERC1967: new admin is the zero address");
        StorageSlot.getAddressSlot(_ADMIN_SLOT).value = newAdmin;
    }
    /**
     * @dev Changes the admin of the proxy.
     *
     * Emits an {AdminChanged} event.
     */
    function _changeAdmin(address newAdmin) internal {
        emit AdminChanged(_getAdmin(), newAdmin);
        _setAdmin(newAdmin);
    }
    /**
     * @dev The storage slot of the UpgradeableBeacon contract which defines the implementation for this proxy.
     * This is bytes32(uint256(keccak256('eip1967.proxy.beacon')) - 1)) and is validated in the constructor.
     */
    bytes32 internal constant _BEACON_SLOT = 0xa3f0ad74e5423aebfd80d3ef4346578335a9a72aeaee59ff6cb3582b35133d50;
    /**
     * @dev Returns the current beacon.
     */
    function _getBeacon() internal view returns (address) {
        return StorageSlot.getAddressSlot(_BEACON_SLOT).value;
    }
    /**
     * @dev Stores a new beacon in the EIP1967 beacon slot.
     */
    function _setBeacon(address newBeacon) private {
        require(Address.isContract(newBeacon), "ERC1967: new beacon is not a contract");
        require(
            Address.isContract(IBeacon(newBeacon).implementation()),
            "ERC1967: beacon implementation is not a contract"
        );
        StorageSlot.getAddressSlot(_BEACON_SLOT).value = newBeacon;
    }
    /**
     * @dev Perform beacon upgrade with additional setup call. Note: This upgrades the address of the beacon, it does
     * not upgrade the implementation contained in the beacon (see {UpgradeableBeacon-_setImplementation} for that).
     *
     * Emits a {BeaconUpgraded} event.
     */
    function _upgradeBeaconToAndCall(
        address newBeacon,
        bytes memory data,
        bool forceCall
    ) internal {
        _setBeacon(newBeacon);
        emit BeaconUpgraded(newBeacon);
        if (data.length > 0 || forceCall) {
            Address.functionDelegateCall(IBeacon(newBeacon).implementation(), data);
        }
    }
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (proxy/Proxy.sol)
pragma solidity ^0.8.0;
/**
 * @dev This abstract contract provides a fallback function that delegates all calls to another contract using the EVM
 * instruction `delegatecall`. We refer to the second contract as the _implementation_ behind the proxy, and it has to
 * be specified by overriding the virtual {_implementation} function.
 *
 * Additionally, delegation to the implementation can be triggered manually through the {_fallback} function, or to a
 * different contract through the {_delegate} function.
 *
 * The success and return data of the delegated call will be returned back to the caller of the proxy.
 */
abstract contract Proxy {
    /**
     * @dev Delegates the current call to `implementation`.
     *
     * This function does not return to its internal call site, it will return directly to the external caller.
     */
    function _delegate(address implementation) internal virtual {
        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 This is a virtual function that should be overridden so it returns the address to which the fallback function
     * and {_fallback} should delegate.
     */
    function _implementation() internal view virtual returns (address);
    /**
     * @dev Delegates the current call to the address returned by `_implementation()`.
     *
     * This function does not return to its internal call site, it will return directly to the external caller.
     */
    function _fallback() internal virtual {
        _beforeFallback();
        _delegate(_implementation());
    }
    /**
     * @dev Fallback function that delegates calls to the address returned by `_implementation()`. Will run if no other
     * function in the contract matches the call data.
     */
    fallback() external payable virtual {
        _fallback();
    }
    /**
     * @dev Fallback function that delegates calls to the address returned by `_implementation()`. Will run if call data
     * is empty.
     */
    receive() external payable virtual {
        _fallback();
    }
    /**
     * @dev Hook that is called before falling back to the implementation. Can happen as part of a manual `_fallback`
     * call, or as part of the Solidity `fallback` or `receive` functions.
     *
     * If overridden should call `super._beforeFallback()`.
     */
    function _beforeFallback() internal virtual {}
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.3) (proxy/transparent/ProxyAdmin.sol)
pragma solidity ^0.8.0;
import "./TransparentUpgradeableProxy.sol";
import "../../access/Ownable.sol";
/**
 * @dev This is an auxiliary contract meant to be assigned as the admin of a {TransparentUpgradeableProxy}. For an
 * explanation of why you would want to use this see the documentation for {TransparentUpgradeableProxy}.
 */
contract ProxyAdmin is Ownable {
    /**
     * @dev Returns the current implementation of `proxy`.
     *
     * Requirements:
     *
     * - This contract must be the admin of `proxy`.
     */
    function getProxyImplementation(ITransparentUpgradeableProxy proxy) public view virtual returns (address) {
        // We need to manually run the static call since the getter cannot be flagged as view
        // bytes4(keccak256("implementation()")) == 0x5c60da1b
        (bool success, bytes memory returndata) = address(proxy).staticcall(hex"5c60da1b");
        require(success);
        return abi.decode(returndata, (address));
    }
    /**
     * @dev Returns the current admin of `proxy`.
     *
     * Requirements:
     *
     * - This contract must be the admin of `proxy`.
     */
    function getProxyAdmin(ITransparentUpgradeableProxy proxy) public view virtual returns (address) {
        // We need to manually run the static call since the getter cannot be flagged as view
        // bytes4(keccak256("admin()")) == 0xf851a440
        (bool success, bytes memory returndata) = address(proxy).staticcall(hex"f851a440");
        require(success);
        return abi.decode(returndata, (address));
    }
    /**
     * @dev Changes the admin of `proxy` to `newAdmin`.
     *
     * Requirements:
     *
     * - This contract must be the current admin of `proxy`.
     */
    function changeProxyAdmin(ITransparentUpgradeableProxy proxy, address newAdmin) public virtual onlyOwner {
        proxy.changeAdmin(newAdmin);
    }
    /**
     * @dev Upgrades `proxy` to `implementation`. See {TransparentUpgradeableProxy-upgradeTo}.
     *
     * Requirements:
     *
     * - This contract must be the admin of `proxy`.
     */
    function upgrade(ITransparentUpgradeableProxy proxy, address implementation) public virtual onlyOwner {
        proxy.upgradeTo(implementation);
    }
    /**
     * @dev Upgrades `proxy` to `implementation` and calls a function on the new implementation. See
     * {TransparentUpgradeableProxy-upgradeToAndCall}.
     *
     * Requirements:
     *
     * - This contract must be the admin of `proxy`.
     */
    function upgradeAndCall(
        ITransparentUpgradeableProxy proxy,
        address implementation,
        bytes memory data
    ) public payable virtual onlyOwner {
        proxy.upgradeToAndCall{value: msg.value}(implementation, data);
    }
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.3) (proxy/transparent/TransparentUpgradeableProxy.sol)
pragma solidity ^0.8.0;
import "../ERC1967/ERC1967Proxy.sol";
/**
 * @dev Interface for {TransparentUpgradeableProxy}. In order to implement transparency, {TransparentUpgradeableProxy}
 * does not implement this interface directly, and some of its functions are implemented by an internal dispatch
 * mechanism. The compiler is unaware that these functions are implemented by {TransparentUpgradeableProxy} and will not
 * include them in the ABI so this interface must be used to interact with it.
 */
interface ITransparentUpgradeableProxy is IERC1967 {
    function admin() external view returns (address);
    function implementation() external view returns (address);
    function changeAdmin(address) external;
    function upgradeTo(address) external;
    function upgradeToAndCall(address, bytes memory) external payable;
}
/**
 * @dev This contract implements a proxy that is upgradeable by an admin.
 *
 * To avoid https://medium.com/nomic-labs-blog/malicious-backdoors-in-ethereum-proxies-62629adf3357[proxy selector
 * clashing], which can potentially be used in an attack, this contract uses the
 * https://blog.openzeppelin.com/the-transparent-proxy-pattern/[transparent proxy pattern]. This pattern implies two
 * things that go hand in hand:
 *
 * 1. If any account other than the admin calls the proxy, the call will be forwarded to the implementation, even if
 * that call matches one of the admin functions exposed by the proxy itself.
 * 2. If the admin calls the proxy, it can access the admin functions, but its calls will never be forwarded to the
 * implementation. If the admin tries to call a function on the implementation it will fail with an error that says
 * "admin cannot fallback to proxy target".
 *
 * These properties mean that the admin account can only be used for admin actions like upgrading the proxy or changing
 * the admin, so it's best if it's a dedicated account that is not used for anything else. This will avoid headaches due
 * to sudden errors when trying to call a function from the proxy implementation.
 *
 * Our recommendation is for the dedicated account to be an instance of the {ProxyAdmin} contract. If set up this way,
 * you should think of the `ProxyAdmin` instance as the real administrative interface of your proxy.
 *
 * NOTE: The real interface of this proxy is that defined in `ITransparentUpgradeableProxy`. This contract does not
 * inherit from that interface, and instead the admin functions are implicitly implemented using a custom dispatch
 * mechanism in `_fallback`. Consequently, the compiler will not produce an ABI for this contract. This is necessary to
 * fully implement transparency without decoding reverts caused by selector clashes between the proxy and the
 * implementation.
 *
 * WARNING: It is not recommended to extend this contract to add additional external functions. If you do so, the compiler
 * will not check that there are no selector conflicts, due to the note above. A selector clash between any new function
 * and the functions declared in {ITransparentUpgradeableProxy} will be resolved in favor of the new one. This could
 * render the admin operations inaccessible, which could prevent upgradeability. Transparency may also be compromised.
 */
contract TransparentUpgradeableProxy is ERC1967Proxy {
    /**
     * @dev Initializes an upgradeable proxy managed by `_admin`, backed by the implementation at `_logic`, and
     * optionally initialized with `_data` as explained in {ERC1967Proxy-constructor}.
     */
    constructor(
        address _logic,
        address admin_,
        bytes memory _data
    ) payable ERC1967Proxy(_logic, _data) {
        _changeAdmin(admin_);
    }
    /**
     * @dev Modifier used internally that will delegate the call to the implementation unless the sender is the admin.
     *
     * CAUTION: This modifier is deprecated, as it could cause issues if the modified function has arguments, and the
     * implementation provides a function with the same selector.
     */
    modifier ifAdmin() {
        if (msg.sender == _getAdmin()) {
            _;
        } else {
            _fallback();
        }
    }
    /**
     * @dev If caller is the admin process the call internally, otherwise transparently fallback to the proxy behavior
     */
    function _fallback() internal virtual override {
        if (msg.sender == _getAdmin()) {
            bytes memory ret;
            bytes4 selector = msg.sig;
            if (selector == ITransparentUpgradeableProxy.upgradeTo.selector) {
                ret = _dispatchUpgradeTo();
            } else if (selector == ITransparentUpgradeableProxy.upgradeToAndCall.selector) {
                ret = _dispatchUpgradeToAndCall();
            } else if (selector == ITransparentUpgradeableProxy.changeAdmin.selector) {
                ret = _dispatchChangeAdmin();
            } else if (selector == ITransparentUpgradeableProxy.admin.selector) {
                ret = _dispatchAdmin();
            } else if (selector == ITransparentUpgradeableProxy.implementation.selector) {
                ret = _dispatchImplementation();
            } else {
                revert("TransparentUpgradeableProxy: admin cannot fallback to proxy target");
            }
            assembly {
                return(add(ret, 0x20), mload(ret))
            }
        } else {
            super._fallback();
        }
    }
    /**
     * @dev Returns the current admin.
     *
     * TIP: To get this value clients can read directly from the storage slot shown below (specified by EIP1967) using the
     * https://eth.wiki/json-rpc/API#eth_getstorageat[`eth_getStorageAt`] RPC call.
     * `0xb53127684a568b3173ae13b9f8a6016e243e63b6e8ee1178d6a717850b5d6103`
     */
    function _dispatchAdmin() private returns (bytes memory) {
        _requireZeroValue();
        address admin = _getAdmin();
        return abi.encode(admin);
    }
    /**
     * @dev Returns the current implementation.
     *
     * TIP: To get this value clients can read directly from the storage slot shown below (specified by EIP1967) using the
     * https://eth.wiki/json-rpc/API#eth_getstorageat[`eth_getStorageAt`] RPC call.
     * `0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc`
     */
    function _dispatchImplementation() private returns (bytes memory) {
        _requireZeroValue();
        address implementation = _implementation();
        return abi.encode(implementation);
    }
    /**
     * @dev Changes the admin of the proxy.
     *
     * Emits an {AdminChanged} event.
     */
    function _dispatchChangeAdmin() private returns (bytes memory) {
        _requireZeroValue();
        address newAdmin = abi.decode(msg.data[4:], (address));
        _changeAdmin(newAdmin);
        return "";
    }
    /**
     * @dev Upgrade the implementation of the proxy.
     */
    function _dispatchUpgradeTo() private returns (bytes memory) {
        _requireZeroValue();
        address newImplementation = abi.decode(msg.data[4:], (address));
        _upgradeToAndCall(newImplementation, bytes(""), false);
        return "";
    }
    /**
     * @dev Upgrade the implementation of the proxy, and then call a function from the new implementation as specified
     * by `data`, which should be an encoded function call. This is useful to initialize new storage variables in the
     * proxied contract.
     */
    function _dispatchUpgradeToAndCall() private returns (bytes memory) {
        (address newImplementation, bytes memory data) = abi.decode(msg.data[4:], (address, bytes));
        _upgradeToAndCall(newImplementation, data, true);
        return "";
    }
    /**
     * @dev Returns the current admin.
     */
    function _admin() internal view virtual returns (address) {
        return _getAdmin();
    }
    /**
     * @dev To keep this contract fully transparent, all `ifAdmin` functions must be payable. This helper is here to
     * emulate some proxy functions being non-payable while still allowing value to pass through.
     */
    function _requireZeroValue() private {
        require(msg.value == 0);
    }
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (utils/Address.sol)
pragma solidity ^0.8.1;
/**
 * @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
     * ====
     *
     * [IMPORTANT]
     * ====
     * You shouldn't rely on `isContract` to protect against flash loan attacks!
     *
     * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
     * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
     * constructor.
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize/address.code.length, which returns 0
        // for contracts in construction, since the code is only stored at the end
        // of the constructor execution.
        return account.code.length > 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");
        (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 functionCallWithValue(target, data, 0, "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");
        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResultFromTarget(target, 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) {
        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResultFromTarget(target, 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) {
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResultFromTarget(target, success, returndata, errorMessage);
    }
    /**
     * @dev Tool to verify that a low level call to smart-contract was successful, and revert (either by bubbling
     * the revert reason or using the provided one) in case of unsuccessful call or if target was not a contract.
     *
     * _Available since v4.8._
     */
    function verifyCallResultFromTarget(
        address target,
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        if (success) {
            if (returndata.length == 0) {
                // only check isContract if the call was successful and the return data is empty
                // otherwise we already know that it was a contract
                require(isContract(target), "Address: call to non-contract");
            }
            return returndata;
        } else {
            _revert(returndata, errorMessage);
        }
    }
    /**
     * @dev Tool to verify that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason or using the provided one.
     *
     * _Available since v4.3._
     */
    function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal pure returns (bytes memory) {
        if (success) {
            return returndata;
        } else {
            _revert(returndata, errorMessage);
        }
    }
    function _revert(bytes memory returndata, string memory errorMessage) private pure {
        // 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
            /// @solidity memory-safe-assembly
            assembly {
                let returndata_size := mload(returndata)
                revert(add(32, returndata), returndata_size)
            }
        } else {
            revert(errorMessage);
        }
    }
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)
pragma solidity ^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 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) {
        return msg.sender;
    }
    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (utils/StorageSlot.sol)
pragma solidity ^0.8.0;
/**
 * @dev Library for reading and writing primitive types to specific storage slots.
 *
 * Storage slots are often used to avoid storage conflict when dealing with upgradeable contracts.
 * This library helps with reading and writing to such slots without the need for inline assembly.
 *
 * The functions in this library return Slot structs that contain a `value` member that can be used to read or write.
 *
 * Example usage to set ERC1967 implementation slot:
 * ```
 * contract ERC1967 {
 *     bytes32 internal constant _IMPLEMENTATION_SLOT = 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc;
 *
 *     function _getImplementation() internal view returns (address) {
 *         return StorageSlot.getAddressSlot(_IMPLEMENTATION_SLOT).value;
 *     }
 *
 *     function _setImplementation(address newImplementation) internal {
 *         require(Address.isContract(newImplementation), "ERC1967: new implementation is not a contract");
 *         StorageSlot.getAddressSlot(_IMPLEMENTATION_SLOT).value = newImplementation;
 *     }
 * }
 * ```
 *
 * _Available since v4.1 for `address`, `bool`, `bytes32`, and `uint256`._
 */
library StorageSlot {
    struct AddressSlot {
        address value;
    }
    struct BooleanSlot {
        bool value;
    }
    struct Bytes32Slot {
        bytes32 value;
    }
    struct Uint256Slot {
        uint256 value;
    }
    /**
     * @dev Returns an `AddressSlot` with member `value` located at `slot`.
     */
    function getAddressSlot(bytes32 slot) internal pure returns (AddressSlot storage r) {
        /// @solidity memory-safe-assembly
        assembly {
            r.slot := slot
        }
    }
    /**
     * @dev Returns an `BooleanSlot` with member `value` located at `slot`.
     */
    function getBooleanSlot(bytes32 slot) internal pure returns (BooleanSlot storage r) {
        /// @solidity memory-safe-assembly
        assembly {
            r.slot := slot
        }
    }
    /**
     * @dev Returns an `Bytes32Slot` with member `value` located at `slot`.
     */
    function getBytes32Slot(bytes32 slot) internal pure returns (Bytes32Slot storage r) {
        /// @solidity memory-safe-assembly
        assembly {
            r.slot := slot
        }
    }
    /**
     * @dev Returns an `Uint256Slot` with member `value` located at `slot`.
     */
    function getUint256Slot(bytes32 slot) internal pure returns (Uint256Slot storage r) {
        /// @solidity memory-safe-assembly
        assembly {
            r.slot := slot
        }
    }
}

// File: contracts/interfaces/IUniswapV2Pair.sol

pragma solidity >=0.5.0;

interface IUniswapV2Pair {
    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    function name() external pure returns (string memory);
    function symbol() external pure returns (string memory);
    function decimals() external pure returns (uint8);
    function totalSupply() external view returns (uint);
    function balanceOf(address owner) external view returns (uint);
    function allowance(address owner, address spender) external view returns (uint);

    function approve(address spender, uint value) external returns (bool);
    function transfer(address to, uint value) external returns (bool);
    function transferFrom(address from, address to, uint value) external returns (bool);

    function DOMAIN_SEPARATOR() external view returns (bytes32);
    function PERMIT_TYPEHASH() external pure returns (bytes32);
    function nonces(address owner) external view returns (uint);

    function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external;

    event Mint(address indexed sender, uint amount0, uint amount1);
    event Burn(address indexed sender, uint amount0, uint amount1, address indexed to);
    event Swap(
        address indexed sender,
        uint amount0In,
        uint amount1In,
        uint amount0Out,
        uint amount1Out,
        address indexed to
    );
    event Sync(uint112 reserve0, uint112 reserve1);

    function MINIMUM_LIQUIDITY() external pure returns (uint);
    function factory() external view returns (address);
    function token0() external view returns (address);
    function token1() external view returns (address);
    function getReserves() external view returns (uint112 reserve0, uint112 reserve1, uint32 blockTimestampLast);
    function price0CumulativeLast() external view returns (uint);
    function price1CumulativeLast() external view returns (uint);
    function kLast() external view returns (uint);

    function mint(address to) external returns (uint liquidity);
    function burn(address to) external returns (uint amount0, uint amount1);
    function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external;
    function skim(address to) external;
    function sync() external;

    function initialize(address, address) external;
}

// File: contracts/interfaces/IUniswapV2ERC20.sol

pragma solidity >=0.5.0;

interface IUniswapV2ERC20 {
    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    function name() external pure returns (string memory);
    function symbol() external pure returns (string memory);
    function decimals() external pure returns (uint8);
    function totalSupply() external view returns (uint);
    function balanceOf(address owner) external view returns (uint);
    function allowance(address owner, address spender) external view returns (uint);

    function approve(address spender, uint value) external returns (bool);
    function transfer(address to, uint value) external returns (bool);
    function transferFrom(address from, address to, uint value) external returns (bool);

    function DOMAIN_SEPARATOR() external view returns (bytes32);
    function PERMIT_TYPEHASH() external pure returns (bytes32);
    function nonces(address owner) external view returns (uint);

    function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external;
}

// File: contracts/libraries/SafeMath.sol

pragma solidity =0.5.16;

// a library for performing overflow-safe math, courtesy of DappHub (https://github.com/dapphub/ds-math)

library SafeMath {
    function add(uint x, uint y) internal pure returns (uint z) {
        require((z = x + y) >= x, 'ds-math-add-overflow');
    }

    function sub(uint x, uint y) internal pure returns (uint z) {
        require((z = x - y) <= x, 'ds-math-sub-underflow');
    }

    function mul(uint x, uint y) internal pure returns (uint z) {
        require(y == 0 || (z = x * y) / y == x, 'ds-math-mul-overflow');
    }
}

// File: contracts/UniswapV2ERC20.sol

pragma solidity =0.5.16;



contract UniswapV2ERC20 is IUniswapV2ERC20 {
    using SafeMath for uint;

    string public constant name = 'Uniswap V2';
    string public constant symbol = 'UNI-V2';
    uint8 public constant decimals = 18;
    uint  public totalSupply;
    mapping(address => uint) public balanceOf;
    mapping(address => mapping(address => uint)) public allowance;

    bytes32 public DOMAIN_SEPARATOR;
    // keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)");
    bytes32 public constant PERMIT_TYPEHASH = 0x6e71edae12b1b97f4d1f60370fef10105fa2faae0126114a169c64845d6126c9;
    mapping(address => uint) public nonces;

    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    constructor() public {
        uint chainId;
        assembly {
            chainId := chainid
        }
        DOMAIN_SEPARATOR = keccak256(
            abi.encode(
                keccak256('EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)'),
                keccak256(bytes(name)),
                keccak256(bytes('1')),
                chainId,
                address(this)
            )
        );
    }

    function _mint(address to, uint value) internal {
        totalSupply = totalSupply.add(value);
        balanceOf[to] = balanceOf[to].add(value);
        emit Transfer(address(0), to, value);
    }

    function _burn(address from, uint value) internal {
        balanceOf[from] = balanceOf[from].sub(value);
        totalSupply = totalSupply.sub(value);
        emit Transfer(from, address(0), value);
    }

    function _approve(address owner, address spender, uint value) private {
        allowance[owner][spender] = value;
        emit Approval(owner, spender, value);
    }

    function _transfer(address from, address to, uint value) private {
        balanceOf[from] = balanceOf[from].sub(value);
        balanceOf[to] = balanceOf[to].add(value);
        emit Transfer(from, to, value);
    }

    function approve(address spender, uint value) external returns (bool) {
        _approve(msg.sender, spender, value);
        return true;
    }

    function transfer(address to, uint value) external returns (bool) {
        _transfer(msg.sender, to, value);
        return true;
    }

    function transferFrom(address from, address to, uint value) external returns (bool) {
        if (allowance[from][msg.sender] != uint(-1)) {
            allowance[from][msg.sender] = allowance[from][msg.sender].sub(value);
        }
        _transfer(from, to, value);
        return true;
    }

    function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external {
        require(deadline >= block.timestamp, 'UniswapV2: EXPIRED');
        bytes32 digest = keccak256(
            abi.encodePacked(
                '\x19\x01',
                DOMAIN_SEPARATOR,
                keccak256(abi.encode(PERMIT_TYPEHASH, owner, spender, value, nonces[owner]++, deadline))
            )
        );
        address recoveredAddress = ecrecover(digest, v, r, s);
        require(recoveredAddress != address(0) && recoveredAddress == owner, 'UniswapV2: INVALID_SIGNATURE');
        _approve(owner, spender, value);
    }
}

// File: contracts/libraries/Math.sol

pragma solidity =0.5.16;

// a library for performing various math operations

library Math {
    function min(uint x, uint y) internal pure returns (uint z) {
        z = x < y ? x : y;
    }

    // babylonian method (https://en.wikipedia.org/wiki/Methods_of_computing_square_roots#Babylonian_method)
    function sqrt(uint y) internal pure returns (uint z) {
        if (y > 3) {
            z = y;
            uint x = y / 2 + 1;
            while (x < z) {
                z = x;
                x = (y / x + x) / 2;
            }
        } else if (y != 0) {
            z = 1;
        }
    }
}

// File: contracts/libraries/UQ112x112.sol

pragma solidity =0.5.16;

// a library for handling binary fixed point numbers (https://en.wikipedia.org/wiki/Q_(number_format))

// range: [0, 2**112 - 1]
// resolution: 1 / 2**112

library UQ112x112 {
    uint224 constant Q112 = 2**112;

    // encode a uint112 as a UQ112x112
    function encode(uint112 y) internal pure returns (uint224 z) {
        z = uint224(y) * Q112; // never overflows
    }

    // divide a UQ112x112 by a uint112, returning a UQ112x112
    function uqdiv(uint224 x, uint112 y) internal pure returns (uint224 z) {
        z = x / uint224(y);
    }
}

// File: contracts/interfaces/IERC20.sol

pragma solidity >=0.5.0;

interface IERC20 {
    event Approval(address indexed owner, address indexed spender, uint value);
    event Transfer(address indexed from, address indexed to, uint value);

    function name() external view returns (string memory);
    function symbol() external view returns (string memory);
    function decimals() external view returns (uint8);
    function totalSupply() external view returns (uint);
    function balanceOf(address owner) external view returns (uint);
    function allowance(address owner, address spender) external view returns (uint);

    function approve(address spender, uint value) external returns (bool);
    function transfer(address to, uint value) external returns (bool);
    function transferFrom(address from, address to, uint value) external returns (bool);
}

// File: contracts/interfaces/IUniswapV2Factory.sol

pragma solidity >=0.5.0;

interface IUniswapV2Factory {
    event PairCreated(address indexed token0, address indexed token1, address pair, uint);

    function feeTo() external view returns (address);
    function feeToSetter() external view returns (address);

    function getPair(address tokenA, address tokenB) external view returns (address pair);
    function allPairs(uint) external view returns (address pair);
    function allPairsLength() external view returns (uint);

    function createPair(address tokenA, address tokenB) external returns (address pair);

    function setFeeTo(address) external;
    function setFeeToSetter(address) external;
}

// File: contracts/interfaces/IUniswapV2Callee.sol

pragma solidity >=0.5.0;

interface IUniswapV2Callee {
    function uniswapV2Call(address sender, uint amount0, uint amount1, bytes calldata data) external;
}

// File: contracts/UniswapV2Pair.sol

pragma solidity =0.5.16;








contract UniswapV2Pair is IUniswapV2Pair, UniswapV2ERC20 {
    using SafeMath  for uint;
    using UQ112x112 for uint224;

    uint public constant MINIMUM_LIQUIDITY = 10**3;
    bytes4 private constant SELECTOR = bytes4(keccak256(bytes('transfer(address,uint256)')));

    address public factory;
    address public token0;
    address public token1;

    uint112 private reserve0;           // uses single storage slot, accessible via getReserves
    uint112 private reserve1;           // uses single storage slot, accessible via getReserves
    uint32  private blockTimestampLast; // uses single storage slot, accessible via getReserves

    uint public price0CumulativeLast;
    uint public price1CumulativeLast;
    uint public kLast; // reserve0 * reserve1, as of immediately after the most recent liquidity event

    uint private unlocked = 1;
    modifier lock() {
        require(unlocked == 1, 'UniswapV2: LOCKED');
        unlocked = 0;
        _;
        unlocked = 1;
    }

    function getReserves() public view returns (uint112 _reserve0, uint112 _reserve1, uint32 _blockTimestampLast) {
        _reserve0 = reserve0;
        _reserve1 = reserve1;
        _blockTimestampLast = blockTimestampLast;
    }

    function _safeTransfer(address token, address to, uint value) private {
        (bool success, bytes memory data) = token.call(abi.encodeWithSelector(SELECTOR, to, value));
        require(success && (data.length == 0 || abi.decode(data, (bool))), 'UniswapV2: TRANSFER_FAILED');
    }

    event Mint(address indexed sender, uint amount0, uint amount1);
    event Burn(address indexed sender, uint amount0, uint amount1, address indexed to);
    event Swap(
        address indexed sender,
        uint amount0In,
        uint amount1In,
        uint amount0Out,
        uint amount1Out,
        address indexed to
    );
    event Sync(uint112 reserve0, uint112 reserve1);

    constructor() public {
        factory = msg.sender;
    }

    // called once by the factory at time of deployment
    function initialize(address _token0, address _token1) external {
        require(msg.sender == factory, 'UniswapV2: FORBIDDEN'); // sufficient check
        token0 = _token0;
        token1 = _token1;
    }

    // update reserves and, on the first call per block, price accumulators
    function _update(uint balance0, uint balance1, uint112 _reserve0, uint112 _reserve1) private {
        require(balance0 <= uint112(-1) && balance1 <= uint112(-1), 'UniswapV2: OVERFLOW');
        uint32 blockTimestamp = uint32(block.timestamp % 2**32);
        uint32 timeElapsed = blockTimestamp - blockTimestampLast; // overflow is desired
        if (timeElapsed > 0 && _reserve0 != 0 && _reserve1 != 0) {
            // * never overflows, and + overflow is desired
            price0CumulativeLast += uint(UQ112x112.encode(_reserve1).uqdiv(_reserve0)) * timeElapsed;
            price1CumulativeLast += uint(UQ112x112.encode(_reserve0).uqdiv(_reserve1)) * timeElapsed;
        }
        reserve0 = uint112(balance0);
        reserve1 = uint112(balance1);
        blockTimestampLast = blockTimestamp;
        emit Sync(reserve0, reserve1);
    }

    // if fee is on, mint liquidity equivalent to 1/6th of the growth in sqrt(k)
    function _mintFee(uint112 _reserve0, uint112 _reserve1) private returns (bool feeOn) {
        address feeTo = IUniswapV2Factory(factory).feeTo();
        feeOn = feeTo != address(0);
        uint _kLast = kLast; // gas savings
        if (feeOn) {
            if (_kLast != 0) {
                uint rootK = Math.sqrt(uint(_reserve0).mul(_reserve1));
                uint rootKLast = Math.sqrt(_kLast);
                if (rootK > rootKLast) {
                    uint numerator = totalSupply.mul(rootK.sub(rootKLast));
                    uint denominator = rootK.mul(5).add(rootKLast);
                    uint liquidity = numerator / denominator;
                    if (liquidity > 0) _mint(feeTo, liquidity);
                }
            }
        } else if (_kLast != 0) {
            kLast = 0;
        }
    }

    // this low-level function should be called from a contract which performs important safety checks
    function mint(address to) external lock returns (uint liquidity) {
        (uint112 _reserve0, uint112 _reserve1,) = getReserves(); // gas savings
        uint balance0 = IERC20(token0).balanceOf(address(this));
        uint balance1 = IERC20(token1).balanceOf(address(this));
        uint amount0 = balance0.sub(_reserve0);
        uint amount1 = balance1.sub(_reserve1);

        bool feeOn = _mintFee(_reserve0, _reserve1);
        uint _totalSupply = totalSupply; // gas savings, must be defined here since totalSupply can update in _mintFee
        if (_totalSupply == 0) {
            liquidity = Math.sqrt(amount0.mul(amount1)).sub(MINIMUM_LIQUIDITY);
           _mint(address(0), MINIMUM_LIQUIDITY); // permanently lock the first MINIMUM_LIQUIDITY tokens
        } else {
            liquidity = Math.min(amount0.mul(_totalSupply) / _reserve0, amount1.mul(_totalSupply) / _reserve1);
        }
        require(liquidity > 0, 'UniswapV2: INSUFFICIENT_LIQUIDITY_MINTED');
        _mint(to, liquidity);

        _update(balance0, balance1, _reserve0, _reserve1);
        if (feeOn) kLast = uint(reserve0).mul(reserve1); // reserve0 and reserve1 are up-to-date
        emit Mint(msg.sender, amount0, amount1);
    }

    // this low-level function should be called from a contract which performs important safety checks
    function burn(address to) external lock returns (uint amount0, uint amount1) {
        (uint112 _reserve0, uint112 _reserve1,) = getReserves(); // gas savings
        address _token0 = token0;                                // gas savings
        address _token1 = token1;                                // gas savings
        uint balance0 = IERC20(_token0).balanceOf(address(this));
        uint balance1 = IERC20(_token1).balanceOf(address(this));
        uint liquidity = balanceOf[address(this)];

        bool feeOn = _mintFee(_reserve0, _reserve1);
        uint _totalSupply = totalSupply; // gas savings, must be defined here since totalSupply can update in _mintFee
        amount0 = liquidity.mul(balance0) / _totalSupply; // using balances ensures pro-rata distribution
        amount1 = liquidity.mul(balance1) / _totalSupply; // using balances ensures pro-rata distribution
        require(amount0 > 0 && amount1 > 0, 'UniswapV2: INSUFFICIENT_LIQUIDITY_BURNED');
        _burn(address(this), liquidity);
        _safeTransfer(_token0, to, amount0);
        _safeTransfer(_token1, to, amount1);
        balance0 = IERC20(_token0).balanceOf(address(this));
        balance1 = IERC20(_token1).balanceOf(address(this));

        _update(balance0, balance1, _reserve0, _reserve1);
        if (feeOn) kLast = uint(reserve0).mul(reserve1); // reserve0 and reserve1 are up-to-date
        emit Burn(msg.sender, amount0, amount1, to);
    }

    // this low-level function should be called from a contract which performs important safety checks
    function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external lock {
        require(amount0Out > 0 || amount1Out > 0, 'UniswapV2: INSUFFICIENT_OUTPUT_AMOUNT');
        (uint112 _reserve0, uint112 _reserve1,) = getReserves(); // gas savings
        require(amount0Out < _reserve0 && amount1Out < _reserve1, 'UniswapV2: INSUFFICIENT_LIQUIDITY');

        uint balance0;
        uint balance1;
        { // scope for _token{0,1}, avoids stack too deep errors
        address _token0 = token0;
        address _token1 = token1;
        require(to != _token0 && to != _token1, 'UniswapV2: INVALID_TO');
        if (amount0Out > 0) _safeTransfer(_token0, to, amount0Out); // optimistically transfer tokens
        if (amount1Out > 0) _safeTransfer(_token1, to, amount1Out); // optimistically transfer tokens
        if (data.length > 0) IUniswapV2Callee(to).uniswapV2Call(msg.sender, amount0Out, amount1Out, data);
        balance0 = IERC20(_token0).balanceOf(address(this));
        balance1 = IERC20(_token1).balanceOf(address(this));
        }
        uint amount0In = balance0 > _reserve0 - amount0Out ? balance0 - (_reserve0 - amount0Out) : 0;
        uint amount1In = balance1 > _reserve1 - amount1Out ? balance1 - (_reserve1 - amount1Out) : 0;
        require(amount0In > 0 || amount1In > 0, 'UniswapV2: INSUFFICIENT_INPUT_AMOUNT');
        { // scope for reserve{0,1}Adjusted, avoids stack too deep errors
        uint balance0Adjusted = balance0.mul(1000).sub(amount0In.mul(3));
        uint balance1Adjusted = balance1.mul(1000).sub(amount1In.mul(3));
        require(balance0Adjusted.mul(balance1Adjusted) >= uint(_reserve0).mul(_reserve1).mul(1000**2), 'UniswapV2: K');
        }

        _update(balance0, balance1, _reserve0, _reserve1);
        emit Swap(msg.sender, amount0In, amount1In, amount0Out, amount1Out, to);
    }

    // force balances to match reserves
    function skim(address to) external lock {
        address _token0 = token0; // gas savings
        address _token1 = token1; // gas savings
        _safeTransfer(_token0, to, IERC20(_token0).balanceOf(address(this)).sub(reserve0));
        _safeTransfer(_token1, to, IERC20(_token1).balanceOf(address(this)).sub(reserve1));
    }

    // force reserves to match balances
    function sync() external lock {
        _update(IERC20(token0).balanceOf(address(this)), IERC20(token1).balanceOf(address(this)), reserve0, reserve1);
    }
}

/**

https://uwu404.com/

*/

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.4;

interface IUniswapV2Router02 {
    function factory() external pure returns (address);

    function WETH() external pure returns (address);

    function addLiquidity(
        address tokenA,
        address tokenB,
        uint256 amountADesired,
        uint256 amountBDesired,
        uint256 amountAMin,
        uint256 amountBMin,
        address to,
        uint256 deadline
    )
    external
    returns (
        uint256 amountA,
        uint256 amountB,
        uint256 liquidity
    );

    function addLiquidityETH(
        address token,
        uint256 amountTokenDesired,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        address to,
        uint256 deadline
    )
    external
    payable
    returns (
        uint256 amountToken,
        uint256 amountETH,
        uint256 liquidity
    );

    function swapExactTokensForETHSupportingFeeOnTransferTokens(
        uint256 amountIn,
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external;
}


/// @notice Library for storage of packed unsigned integers.
/// @author Solady (https://github.com/vectorized/solady/blob/main/src/utils/LibMap.sol)
library LibMap {
    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                          STRUCTS                           */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev A uint8 map in storage.
    struct Uint8Map {
        mapping(uint256 => uint256) map;
    }

    /// @dev A uint16 map in storage.
    struct Uint16Map {
        mapping(uint256 => uint256) map;
    }

    /// @dev A uint32 map in storage.
    struct Uint32Map {
        mapping(uint256 => uint256) map;
    }

    /// @dev A uint40 map in storage. Useful for storing timestamps up to 34841 A.D.
    struct Uint40Map {
        mapping(uint256 => uint256) map;
    }

    /// @dev A uint64 map in storage.
    struct Uint64Map {
        mapping(uint256 => uint256) map;
    }

    /// @dev A uint128 map in storage.
    struct Uint128Map {
        mapping(uint256 => uint256) map;
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                     GETTERS / SETTERS                      */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Returns the uint8 value at `index` in `map`.
    function get(Uint8Map storage map, uint256 index) internal view returns (uint8 result) {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x20, map.slot)
            mstore(0x00, shr(5, index))
            result := byte(and(31, not(index)), sload(keccak256(0x00, 0x40)))
        }
    }

    /// @dev Updates the uint8 value at `index` in `map`.
    function set(Uint8Map storage map, uint256 index, uint8 value) internal {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x20, map.slot)
            mstore(0x00, shr(5, index))
            let s := keccak256(0x00, 0x40) // Storage slot.
            mstore(0x00, sload(s))
            mstore8(and(31, not(index)), value)
            sstore(s, mload(0x00))
        }
    }

    /// @dev Returns the uint16 value at `index` in `map`.
    function get(Uint16Map storage map, uint256 index) internal view returns (uint16 result) {
        result = uint16(map.map[index >> 4] >> ((index & 15) << 4));
    }

    /// @dev Updates the uint16 value at `index` in `map`.
    function set(Uint16Map storage map, uint256 index, uint16 value) internal {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x20, map.slot)
            mstore(0x00, shr(4, index))
            let s := keccak256(0x00, 0x40) // Storage slot.
            let o := shl(4, and(index, 15)) // Storage slot offset (bits).
            let v := sload(s) // Storage slot value.
            let m := 0xffff // Value mask.
            sstore(s, xor(v, shl(o, and(m, xor(shr(o, v), value)))))
        }
    }

    /// @dev Returns the uint32 value at `index` in `map`.
    function get(Uint32Map storage map, uint256 index) internal view returns (uint32 result) {
        result = uint32(map.map[index >> 3] >> ((index & 7) << 5));
    }

    /// @dev Updates the uint32 value at `index` in `map`.
    function set(Uint32Map storage map, uint256 index, uint32 value) internal {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x20, map.slot)
            mstore(0x00, shr(3, index))
            let s := keccak256(0x00, 0x40) // Storage slot.
            let o := shl(5, and(index, 7)) // Storage slot offset (bits).
            let v := sload(s) // Storage slot value.
            let m := 0xffffffff // Value mask.
            sstore(s, xor(v, shl(o, and(m, xor(shr(o, v), value)))))
        }
    }

    /// @dev Returns the uint40 value at `index` in `map`.
    function get(Uint40Map storage map, uint256 index) internal view returns (uint40 result) {
        unchecked {
            result = uint40(map.map[index / 6] >> ((index % 6) * 40));
        }
    }

    /// @dev Updates the uint40 value at `index` in `map`.
    function set(Uint40Map storage map, uint256 index, uint40 value) internal {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x20, map.slot)
            mstore(0x00, div(index, 6))
            let s := keccak256(0x00, 0x40) // Storage slot.
            let o := mul(40, mod(index, 6)) // Storage slot offset (bits).
            let v := sload(s) // Storage slot value.
            let m := 0xffffffffff // Value mask.
            sstore(s, xor(v, shl(o, and(m, xor(shr(o, v), value)))))
        }
    }

    /// @dev Returns the uint64 value at `index` in `map`.
    function get(Uint64Map storage map, uint256 index) internal view returns (uint64 result) {
        result = uint64(map.map[index >> 2] >> ((index & 3) << 6));
    }

    /// @dev Updates the uint64 value at `index` in `map`.
    function set(Uint64Map storage map, uint256 index, uint64 value) internal {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x20, map.slot)
            mstore(0x00, shr(2, index))
            let s := keccak256(0x00, 0x40) // Storage slot.
            let o := shl(6, and(index, 3)) // Storage slot offset (bits).
            let v := sload(s) // Storage slot value.
            let m := 0xffffffffffffffff // Value mask.
            sstore(s, xor(v, shl(o, and(m, xor(shr(o, v), value)))))
        }
    }

    /// @dev Returns the uint128 value at `index` in `map`.
    function get(Uint128Map storage map, uint256 index) internal view returns (uint128 result) {
        result = uint128(map.map[index >> 1] >> ((index & 1) << 7));
    }

    /// @dev Updates the uint128 value at `index` in `map`.
    function set(Uint128Map storage map, uint256 index, uint128 value) internal {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x20, map.slot)
            mstore(0x00, shr(1, index))
            let s := keccak256(0x00, 0x40) // Storage slot.
            let o := shl(7, and(index, 1)) // Storage slot offset (bits).
            let v := sload(s) // Storage slot value.
            let m := 0xffffffffffffffffffffffffffffffff // Value mask.
            sstore(s, xor(v, shl(o, and(m, xor(shr(o, v), value)))))
        }
    }

    /// @dev Returns the value at `index` in `map`.
    function get(mapping(uint256 => uint256) storage map, uint256 index, uint256 bitWidth)
    internal
    view
    returns (uint256 result)
    {
        unchecked {
            uint256 d = _rawDiv(256, bitWidth); // Bucket size.
            uint256 m = (1 << bitWidth) - 1; // Value mask.
            result = (map[_rawDiv(index, d)] >> (_rawMod(index, d) * bitWidth)) & m;
        }
    }

    /// @dev Updates the value at `index` in `map`.
    function set(
        mapping(uint256 => uint256) storage map,
        uint256 index,
        uint256 value,
        uint256 bitWidth
    ) internal {
        unchecked {
            uint256 d = _rawDiv(256, bitWidth); // Bucket size.
            uint256 m = (1 << bitWidth) - 1; // Value mask.
            uint256 o = _rawMod(index, d) * bitWidth; // Storage slot offset (bits).
            map[_rawDiv(index, d)] ^= (((map[_rawDiv(index, d)] >> o) ^ value) & m) << o;
        }
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                       BINARY SEARCH                        */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    // The following functions search in the range of [`start`, `end`)
    // (i.e. `start <= index < end`).
    // The range must be sorted in ascending order.
    // `index` precedence: equal to > nearest before > nearest after.
    // An invalid search range will simply return `(found = false, index = start)`.

    /// @dev Returns whether `map` contains `needle`, and the index of `needle`.
    function searchSorted(Uint8Map storage map, uint8 needle, uint256 start, uint256 end)
    internal
    view
    returns (bool found, uint256 index)
    {
        return searchSorted(map.map, needle, start, end, 8);
    }

    /// @dev Returns whether `map` contains `needle`, and the index of `needle`.
    function searchSorted(Uint16Map storage map, uint16 needle, uint256 start, uint256 end)
    internal
    view
    returns (bool found, uint256 index)
    {
        return searchSorted(map.map, needle, start, end, 16);
    }

    /// @dev Returns whether `map` contains `needle`, and the index of `needle`.
    function searchSorted(Uint32Map storage map, uint32 needle, uint256 start, uint256 end)
    internal
    view
    returns (bool found, uint256 index)
    {
        return searchSorted(map.map, needle, start, end, 32);
    }

    /// @dev Returns whether `map` contains `needle`, and the index of `needle`.
    function searchSorted(Uint40Map storage map, uint40 needle, uint256 start, uint256 end)
    internal
    view
    returns (bool found, uint256 index)
    {
        return searchSorted(map.map, needle, start, end, 40);
    }

    /// @dev Returns whether `map` contains `needle`, and the index of `needle`.
    function searchSorted(Uint64Map storage map, uint64 needle, uint256 start, uint256 end)
    internal
    view
    returns (bool found, uint256 index)
    {
        return searchSorted(map.map, needle, start, end, 64);
    }

    /// @dev Returns whether `map` contains `needle`, and the index of `needle`.
    function searchSorted(Uint128Map storage map, uint128 needle, uint256 start, uint256 end)
    internal
    view
    returns (bool found, uint256 index)
    {
        return searchSorted(map.map, needle, start, end, 128);
    }

    /// @dev Returns whether `map` contains `needle`, and the index of `needle`.
    function searchSorted(
        mapping(uint256 => uint256) storage map,
        uint256 needle,
        uint256 start,
        uint256 end,
        uint256 bitWidth
    ) internal view returns (bool found, uint256 index) {
        unchecked {
            if (start >= end) end = start;
            uint256 t;
            uint256 o = start - 1; // Offset to derive the actual index.
            uint256 l = 1; // Low.
            uint256 d = _rawDiv(256, bitWidth); // Bucket size.
            uint256 m = (1 << bitWidth) - 1; // Value mask.
            uint256 h = end - start; // High.
            while (true) {
                index = (l & h) + ((l ^ h) >> 1);
                if (l > h) break;
                t = (map[_rawDiv(index + o, d)] >> (_rawMod(index + o, d) * bitWidth)) & m;
                if (t == needle) break;
                if (needle <= t) h = index - 1;
                else l = index + 1;
            }
        /// @solidity memory-safe-assembly
            assembly {
                m := or(iszero(index), iszero(bitWidth))
                found := iszero(or(xor(t, needle), m))
                index := add(o, xor(index, mul(xor(index, 1), m)))
            }
        }
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                      PRIVATE HELPERS                       */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Returns `x / y`, returning 0 if `y` is zero.
    function _rawDiv(uint256 x, uint256 y) private pure returns (uint256 z) {
        /// @solidity memory-safe-assembly
        assembly {
            z := div(x, y)
        }
    }

    /// @dev Returns `x % y`, returning 0 if `y` is zero.
    function _rawMod(uint256 x, uint256 y) private pure returns (uint256 z) {
        /// @solidity memory-safe-assembly
        assembly {
            z := mod(x, y)
        }
    }
}

/// @notice Library for converting numbers into strings and other string operations.
/// @author Solady (https://github.com/vectorized/solady/blob/main/src/utils/LibString.sol)
/// @author Modified from Solmate (https://github.com/transmissions11/solmate/blob/main/src/utils/LibString.sol)
///
/// @dev Note:
/// For performance and bytecode compactness, most of the string operations are restricted to
/// byte strings (7-bit ASCII), except where otherwise specified.
/// Usage of byte string operations on charsets with runes spanning two or more bytes
/// can lead to undefined behavior.
library LibString {
    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                        CUSTOM ERRORS                       */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev The length of the output is too small to contain all the hex digits.
    error HexLengthInsufficient();

    /// @dev The length of the string is more than 32 bytes.
    error TooBigForSmallString();

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                         CONSTANTS                          */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev The constant returned when the `search` is not found in the string.
    uint256 internal constant NOT_FOUND = type(uint256).max;

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                     DECIMAL OPERATIONS                     */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Returns the base 10 decimal representation of `value`.
    function toString(uint256 value) internal pure returns (string memory str) {
        /// @solidity memory-safe-assembly
        assembly {
        // The maximum value of a uint256 contains 78 digits (1 byte per digit), but
        // we allocate 0xa0 bytes to keep the free memory pointer 32-byte word aligned.
        // We will need 1 word for the trailing zeros padding, 1 word for the length,
        // and 3 words for a maximum of 78 digits.
            str := add(mload(0x40), 0x80)
        // Update the free memory pointer to allocate.
            mstore(0x40, add(str, 0x20))
        // Zeroize the slot after the string.
            mstore(str, 0)

        // Cache the end of the memory to calculate the length later.
            let end := str

            let w := not(0) // Tsk.
        // We write the string from rightmost digit to leftmost digit.
        // The following is essentially a do-while loop that also handles the zero case.
            for { let temp := value } 1 {} {
                str := add(str, w) // `sub(str, 1)`.
            // Write the character to the pointer.
            // The ASCII index of the '0' character is 48.
                mstore8(str, add(48, mod(temp, 10)))
            // Keep dividing `temp` until zero.
                temp := div(temp, 10)
                if iszero(temp) { break }
            }

            let length := sub(end, str)
        // Move the pointer 32 bytes leftwards to make room for the length.
            str := sub(str, 0x20)
        // Store the length.
            mstore(str, length)
        }
    }

    /// @dev Returns the base 10 decimal representation of `value`.
    function toString(int256 value) internal pure returns (string memory str) {
        if (value >= 0) {
            return toString(uint256(value));
        }
        unchecked {
            str = toString(~uint256(value) + 1);
        }
        /// @solidity memory-safe-assembly
        assembly {
        // We still have some spare memory space on the left,
        // as we have allocated 3 words (96 bytes) for up to 78 digits.
            let length := mload(str) // Load the string length.
            mstore(str, 0x2d) // Store the '-' character.
            str := sub(str, 1) // Move back the string pointer by a byte.
            mstore(str, add(length, 1)) // Update the string length.
        }
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                   HEXADECIMAL OPERATIONS                   */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Returns the hexadecimal representation of `value`,
    /// left-padded to an input length of `length` bytes.
    /// The output is prefixed with "0x" encoded using 2 hexadecimal digits per byte,
    /// giving a total length of `length * 2 + 2` bytes.
    /// Reverts if `length` is too small for the output to contain all the digits.
    function toHexString(uint256 value, uint256 length) internal pure returns (string memory str) {
        str = toHexStringNoPrefix(value, length);
        /// @solidity memory-safe-assembly
        assembly {
            let strLength := add(mload(str), 2) // Compute the length.
            mstore(str, 0x3078) // Write the "0x" prefix.
            str := sub(str, 2) // Move the pointer.
            mstore(str, strLength) // Write the length.
        }
    }

    /// @dev Returns the hexadecimal representation of `value`,
    /// left-padded to an input length of `length` bytes.
    /// The output is prefixed with "0x" encoded using 2 hexadecimal digits per byte,
    /// giving a total length of `length * 2` bytes.
    /// Reverts if `length` is too small for the output to contain all the digits.
    function toHexStringNoPrefix(uint256 value, uint256 length)
    internal
    pure
    returns (string memory str)
    {
        /// @solidity memory-safe-assembly
        assembly {
        // We need 0x20 bytes for the trailing zeros padding, `length * 2` bytes
        // for the digits, 0x02 bytes for the prefix, and 0x20 bytes for the length.
        // We add 0x20 to the total and round down to a multiple of 0x20.
        // (0x20 + 0x20 + 0x02 + 0x20) = 0x62.
            str := add(mload(0x40), and(add(shl(1, length), 0x42), not(0x1f)))
        // Allocate the memory.
            mstore(0x40, add(str, 0x20))
        // Zeroize the slot after the string.
            mstore(str, 0)

        // Cache the end to calculate the length later.
            let end := str
        // Store "0123456789abcdef" in scratch space.
            mstore(0x0f, 0x30313233343536373839616263646566)

            let start := sub(str, add(length, length))
            let w := not(1) // Tsk.
            let temp := value
        // We write the string from rightmost digit to leftmost digit.
        // The following is essentially a do-while loop that also handles the zero case.
            for {} 1 {} {
                str := add(str, w) // `sub(str, 2)`.
                mstore8(add(str, 1), mload(and(temp, 15)))
                mstore8(str, mload(and(shr(4, temp), 15)))
                temp := shr(8, temp)
                if iszero(xor(str, start)) { break }
            }

            if temp {
                mstore(0x00, 0x2194895a) // `HexLengthInsufficient()`.
                revert(0x1c, 0x04)
            }

        // Compute the string's length.
            let strLength := sub(end, str)
        // Move the pointer and write the length.
            str := sub(str, 0x20)
            mstore(str, strLength)
        }
    }

    /// @dev Returns the hexadecimal representation of `value`.
    /// The output is prefixed with "0x" and encoded using 2 hexadecimal digits per byte.
    /// As address are 20 bytes long, the output will left-padded to have
    /// a length of `20 * 2 + 2` bytes.
    function toHexString(uint256 value) internal pure returns (string memory str) {
        str = toHexStringNoPrefix(value);
        /// @solidity memory-safe-assembly
        assembly {
            let strLength := add(mload(str), 2) // Compute the length.
            mstore(str, 0x3078) // Write the "0x" prefix.
            str := sub(str, 2) // Move the pointer.
            mstore(str, strLength) // Write the length.
        }
    }

    /// @dev Returns the hexadecimal representation of `value`.
    /// The output is prefixed with "0x".
    /// The output excludes leading "0" from the `toHexString` output.
    /// `0x00: "0x0", 0x01: "0x1", 0x12: "0x12", 0x123: "0x123"`.
    function toMinimalHexString(uint256 value) internal pure returns (string memory str) {
        str = toHexStringNoPrefix(value);
        /// @solidity memory-safe-assembly
        assembly {
            let o := eq(byte(0, mload(add(str, 0x20))), 0x30) // Whether leading zero is present.
            let strLength := add(mload(str), 2) // Compute the length.
            mstore(add(str, o), 0x3078) // Write the "0x" prefix, accounting for leading zero.
            str := sub(add(str, o), 2) // Move the pointer, accounting for leading zero.
            mstore(str, sub(strLength, o)) // Write the length, accounting for leading zero.
        }
    }

    /// @dev Returns the hexadecimal representation of `value`.
    /// The output excludes leading "0" from the `toHexStringNoPrefix` output.
    /// `0x00: "0", 0x01: "1", 0x12: "12", 0x123: "123"`.
    function toMinimalHexStringNoPrefix(uint256 value) internal pure returns (string memory str) {
        str = toHexStringNoPrefix(value);
        /// @solidity memory-safe-assembly
        assembly {
            let o := eq(byte(0, mload(add(str, 0x20))), 0x30) // Whether leading zero is present.
            let strLength := mload(str) // Get the length.
            str := add(str, o) // Move the pointer, accounting for leading zero.
            mstore(str, sub(strLength, o)) // Write the length, accounting for leading zero.
        }
    }

    /// @dev Returns the hexadecimal representation of `value`.
    /// The output is encoded using 2 hexadecimal digits per byte.
    /// As address are 20 bytes long, the output will left-padded to have
    /// a length of `20 * 2` bytes.
    function toHexStringNoPrefix(uint256 value) internal pure returns (string memory str) {
        /// @solidity memory-safe-assembly
        assembly {
        // We need 0x20 bytes for the trailing zeros padding, 0x20 bytes for the length,
        // 0x02 bytes for the prefix, and 0x40 bytes for the digits.
        // The next multiple of 0x20 above (0x20 + 0x20 + 0x02 + 0x40) is 0xa0.
            str := add(mload(0x40), 0x80)
        // Allocate the memory.
            mstore(0x40, add(str, 0x20))
        // Zeroize the slot after the string.
            mstore(str, 0)

        // Cache the end to calculate the length later.
            let end := str
        // Store "0123456789abcdef" in scratch space.
            mstore(0x0f, 0x30313233343536373839616263646566)

            let w := not(1) // Tsk.
        // We write the string from rightmost digit to leftmost digit.
        // The following is essentially a do-while loop that also handles the zero case.
            for { let temp := value } 1 {} {
                str := add(str, w) // `sub(str, 2)`.
                mstore8(add(str, 1), mload(and(temp, 15)))
                mstore8(str, mload(and(shr(4, temp), 15)))
                temp := shr(8, temp)
                if iszero(temp) { break }
            }

        // Compute the string's length.
            let strLength := sub(end, str)
        // Move the pointer and write the length.
            str := sub(str, 0x20)
            mstore(str, strLength)
        }
    }

    /// @dev Returns the hexadecimal representation of `value`.
    /// The output is prefixed with "0x", encoded using 2 hexadecimal digits per byte,
    /// and the alphabets are capitalized conditionally according to
    /// https://eips.ethereum.org/EIPS/eip-55
    function toHexStringChecksummed(address value) internal pure returns (string memory str) {
        str = toHexString(value);
        /// @solidity memory-safe-assembly
        assembly {
            let mask := shl(6, div(not(0), 255)) // `0b010000000100000000 ...`
            let o := add(str, 0x22)
            let hashed := and(keccak256(o, 40), mul(34, mask)) // `0b10001000 ... `
            let t := shl(240, 136) // `0b10001000 << 240`
            for { let i := 0 } 1 {} {
                mstore(add(i, i), mul(t, byte(i, hashed)))
                i := add(i, 1)
                if eq(i, 20) { break }
            }
            mstore(o, xor(mload(o), shr(1, and(mload(0x00), and(mload(o), mask)))))
            o := add(o, 0x20)
            mstore(o, xor(mload(o), shr(1, and(mload(0x20), and(mload(o), mask)))))
        }
    }

    /// @dev Returns the hexadecimal representation of `value`.
    /// The output is prefixed with "0x" and encoded using 2 hexadecimal digits per byte.
    function toHexString(address value) internal pure returns (string memory str) {
        str = toHexStringNoPrefix(value);
        /// @solidity memory-safe-assembly
        assembly {
            let strLength := add(mload(str), 2) // Compute the length.
            mstore(str, 0x3078) // Write the "0x" prefix.
            str := sub(str, 2) // Move the pointer.
            mstore(str, strLength) // Write the length.
        }
    }

    /// @dev Returns the hexadecimal representation of `value`.
    /// The output is encoded using 2 hexadecimal digits per byte.
    function toHexStringNoPrefix(address value) internal pure returns (string memory str) {
        /// @solidity memory-safe-assembly
        assembly {
            str := mload(0x40)

        // Allocate the memory.
        // We need 0x20 bytes for the trailing zeros padding, 0x20 bytes for the length,
        // 0x02 bytes for the prefix, and 0x28 bytes for the digits.
        // The next multiple of 0x20 above (0x20 + 0x20 + 0x02 + 0x28) is 0x80.
            mstore(0x40, add(str, 0x80))

        // Store "0123456789abcdef" in scratch space.
            mstore(0x0f, 0x30313233343536373839616263646566)

            str := add(str, 2)
            mstore(str, 40)

            let o := add(str, 0x20)
            mstore(add(o, 40), 0)

            value := shl(96, value)

        // We write the string from rightmost digit to leftmost digit.
        // The following is essentially a do-while loop that also handles the zero case.
            for { let i := 0 } 1 {} {
                let p := add(o, add(i, i))
                let temp := byte(i, value)
                mstore8(add(p, 1), mload(and(temp, 15)))
                mstore8(p, mload(shr(4, temp)))
                i := add(i, 1)
                if eq(i, 20) { break }
            }
        }
    }

    /// @dev Returns the hex encoded string from the raw bytes.
    /// The output is encoded using 2 hexadecimal digits per byte.
    function toHexString(bytes memory raw) internal pure returns (string memory str) {
        str = toHexStringNoPrefix(raw);
        /// @solidity memory-safe-assembly
        assembly {
            let strLength := add(mload(str), 2) // Compute the length.
            mstore(str, 0x3078) // Write the "0x" prefix.
            str := sub(str, 2) // Move the pointer.
            mstore(str, strLength) // Write the length.
        }
    }

    /// @dev Returns the hex encoded string from the raw bytes.
    /// The output is encoded using 2 hexadecimal digits per byte.
    function toHexStringNoPrefix(bytes memory raw) internal pure returns (string memory str) {
        /// @solidity memory-safe-assembly
        assembly {
            let length := mload(raw)
            str := add(mload(0x40), 2) // Skip 2 bytes for the optional prefix.
            mstore(str, add(length, length)) // Store the length of the output.

        // Store "0123456789abcdef" in scratch space.
            mstore(0x0f, 0x30313233343536373839616263646566)

            let o := add(str, 0x20)
            let end := add(raw, length)

            for {} iszero(eq(raw, end)) {} {
                raw := add(raw, 1)
                mstore8(add(o, 1), mload(and(mload(raw), 15)))
                mstore8(o, mload(and(shr(4, mload(raw)), 15)))
                o := add(o, 2)
            }
            mstore(o, 0) // Zeroize the slot after the string.
            mstore(0x40, add(o, 0x20)) // Allocate the memory.
        }
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                   RUNE STRING OPERATIONS                   */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Returns the number of UTF characters in the string.
    function runeCount(string memory s) internal pure returns (uint256 result) {
        /// @solidity memory-safe-assembly
        assembly {
            if mload(s) {
                mstore(0x00, div(not(0), 255))
                mstore(0x20, 0x0202020202020202020202020202020202020202020202020303030304040506)
                let o := add(s, 0x20)
                let end := add(o, mload(s))
                for { result := 1 } 1 { result := add(result, 1) } {
                    o := add(o, byte(0, mload(shr(250, mload(o)))))
                    if iszero(lt(o, end)) { break }
                }
            }
        }
    }

    /// @dev Returns if this string is a 7-bit ASCII string.
    /// (i.e. all characters codes are in [0..127])
    function is7BitASCII(string memory s) internal pure returns (bool result) {
        /// @solidity memory-safe-assembly
        assembly {
            let mask := shl(7, div(not(0), 255))
            result := 1
            let n := mload(s)
            if n {
                let o := add(s, 0x20)
                let end := add(o, n)
                let last := mload(end)
                mstore(end, 0)
                for {} 1 {} {
                    if and(mask, mload(o)) {
                        result := 0
                        break
                    }
                    o := add(o, 0x20)
                    if iszero(lt(o, end)) { break }
                }
                mstore(end, last)
            }
        }
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                   BYTE STRING OPERATIONS                   */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    // For performance and bytecode compactness, byte string operations are restricted
    // to 7-bit ASCII strings. All offsets are byte offsets, not UTF character offsets.
    // Usage of byte string operations on charsets with runes spanning two or more bytes
    // can lead to undefined behavior.

    /// @dev Returns `subject` all occurrences of `search` replaced with `replacement`.
    function replace(string memory subject, string memory search, string memory replacement)
    internal
    pure
    returns (string memory result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            let subjectLength := mload(subject)
            let searchLength := mload(search)
            let replacementLength := mload(replacement)

            subject := add(subject, 0x20)
            search := add(search, 0x20)
            replacement := add(replacement, 0x20)
            result := add(mload(0x40), 0x20)

            let subjectEnd := add(subject, subjectLength)
            if iszero(gt(searchLength, subjectLength)) {
                let subjectSearchEnd := add(sub(subjectEnd, searchLength), 1)
                let h := 0
                if iszero(lt(searchLength, 0x20)) { h := keccak256(search, searchLength) }
                let m := shl(3, sub(0x20, and(searchLength, 0x1f)))
                let s := mload(search)
                for {} 1 {} {
                    let t := mload(subject)
                // Whether the first `searchLength % 32` bytes of
                // `subject` and `search` matches.
                    if iszero(shr(m, xor(t, s))) {
                        if h {
                            if iszero(eq(keccak256(subject, searchLength), h)) {
                                mstore(result, t)
                                result := add(result, 1)
                                subject := add(subject, 1)
                                if iszero(lt(subject, subjectSearchEnd)) { break }
                                continue
                            }
                        }
                    // Copy the `replacement` one word at a time.
                        for { let o := 0 } 1 {} {
                            mstore(add(result, o), mload(add(replacement, o)))
                            o := add(o, 0x20)
                            if iszero(lt(o, replacementLength)) { break }
                        }
                        result := add(result, replacementLength)
                        subject := add(subject, searchLength)
                        if searchLength {
                            if iszero(lt(subject, subjectSearchEnd)) { break }
                            continue
                        }
                    }
                    mstore(result, t)
                    result := add(result, 1)
                    subject := add(subject, 1)
                    if iszero(lt(subject, subjectSearchEnd)) { break }
                }
            }

            let resultRemainder := result
            result := add(mload(0x40), 0x20)
            let k := add(sub(resultRemainder, result), sub(subjectEnd, subject))
        // Copy the rest of the string one word at a time.
            for {} lt(subject, subjectEnd) {} {
                mstore(resultRemainder, mload(subject))
                resultRemainder := add(resultRemainder, 0x20)
                subject := add(subject, 0x20)
            }
            result := sub(result, 0x20)
            let last := add(add(result, 0x20), k) // Zeroize the slot after the string.
            mstore(last, 0)
            mstore(0x40, add(last, 0x20)) // Allocate the memory.
            mstore(result, k) // Store the length.
        }
    }

    /// @dev Returns the byte index of the first location of `search` in `subject`,
    /// searching from left to right, starting from `from`.
    /// Returns `NOT_FOUND` (i.e. `type(uint256).max`) if the `search` is not found.
    function indexOf(string memory subject, string memory search, uint256 from)
    internal
    pure
    returns (uint256 result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            for { let subjectLength := mload(subject) } 1 {} {
                if iszero(mload(search)) {
                    if iszero(gt(from, subjectLength)) {
                        result := from
                        break
                    }
                    result := subjectLength
                    break
                }
                let searchLength := mload(search)
                let subjectStart := add(subject, 0x20)

                result := not(0) // Initialize to `NOT_FOUND`.

                subject := add(subjectStart, from)
                let end := add(sub(add(subjectStart, subjectLength), searchLength), 1)

                let m := shl(3, sub(0x20, and(searchLength, 0x1f)))
                let s := mload(add(search, 0x20))

                if iszero(and(lt(subject, end), lt(from, subjectLength))) { break }

                if iszero(lt(searchLength, 0x20)) {
                    for { let h := keccak256(add(search, 0x20), searchLength) } 1 {} {
                        if iszero(shr(m, xor(mload(subject), s))) {
                            if eq(keccak256(subject, searchLength), h) {
                                result := sub(subject, subjectStart)
                                break
                            }
                        }
                        subject := add(subject, 1)
                        if iszero(lt(subject, end)) { break }
                    }
                    break
                }
                for {} 1 {} {
                    if iszero(shr(m, xor(mload(subject), s))) {
                        result := sub(subject, subjectStart)
                        break
                    }
                    subject := add(subject, 1)
                    if iszero(lt(subject, end)) { break }
                }
                break
            }
        }
    }

    /// @dev Returns the byte index of the first location of `search` in `subject`,
    /// searching from left to right.
    /// Returns `NOT_FOUND` (i.e. `type(uint256).max`) if the `search` is not found.
    function indexOf(string memory subject, string memory search)
    internal
    pure
    returns (uint256 result)
    {
        result = indexOf(subject, search, 0);
    }

    /// @dev Returns the byte index of the first location of `search` in `subject`,
    /// searching from right to left, starting from `from`.
    /// Returns `NOT_FOUND` (i.e. `type(uint256).max`) if the `search` is not found.
    function lastIndexOf(string memory subject, string memory search, uint256 from)
    internal
    pure
    returns (uint256 result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            for {} 1 {} {
                result := not(0) // Initialize to `NOT_FOUND`.
                let searchLength := mload(search)
                if gt(searchLength, mload(subject)) { break }
                let w := result

                let fromMax := sub(mload(subject), searchLength)
                if iszero(gt(fromMax, from)) { from := fromMax }

                let end := add(add(subject, 0x20), w)
                subject := add(add(subject, 0x20), from)
                if iszero(gt(subject, end)) { break }
            // As this function is not too often used,
            // we shall simply use keccak256 for smaller bytecode size.
                for { let h := keccak256(add(search, 0x20), searchLength) } 1 {} {
                    if eq(keccak256(subject, searchLength), h) {
                        result := sub(subject, add(end, 1))
                        break
                    }
                    subject := add(subject, w) // `sub(subject, 1)`.
                    if iszero(gt(subject, end)) { break }
                }
                break
            }
        }
    }

    /// @dev Returns the byte index of the first location of `search` in `subject`,
    /// searching from right to left.
    /// Returns `NOT_FOUND` (i.e. `type(uint256).max`) if the `search` is not found.
    function lastIndexOf(string memory subject, string memory search)
    internal
    pure
    returns (uint256 result)
    {
        result = lastIndexOf(subject, search, uint256(int256(-1)));
    }

    /// @dev Returns true if `search` is found in `subject`, false otherwise.
    function contains(string memory subject, string memory search) internal pure returns (bool) {
        return indexOf(subject, search) != NOT_FOUND;
    }

    /// @dev Returns whether `subject` starts with `search`.
    function startsWith(string memory subject, string memory search)
    internal
    pure
    returns (bool result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            let searchLength := mload(search)
        // Just using keccak256 directly is actually cheaper.
        // forgefmt: disable-next-item
            result := and(
                iszero(gt(searchLength, mload(subject))),
                eq(
                    keccak256(add(subject, 0x20), searchLength),
                    keccak256(add(search, 0x20), searchLength)
                )
            )
        }
    }

    /// @dev Returns whether `subject` ends with `search`.
    function endsWith(string memory subject, string memory search)
    internal
    pure
    returns (bool result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            let searchLength := mload(search)
            let subjectLength := mload(subject)
        // Whether `search` is not longer than `subject`.
            let withinRange := iszero(gt(searchLength, subjectLength))
        // Just using keccak256 directly is actually cheaper.
        // forgefmt: disable-next-item
            result := and(
                withinRange,
                eq(
                    keccak256(
                    // `subject + 0x20 + max(subjectLength - searchLength, 0)`.
                        add(add(subject, 0x20), mul(withinRange, sub(subjectLength, searchLength))),
                        searchLength
                    ),
                    keccak256(add(search, 0x20), searchLength)
                )
            )
        }
    }

    /// @dev Returns `subject` repeated `times`.
    function repeat(string memory subject, uint256 times)
    internal
    pure
    returns (string memory result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            let subjectLength := mload(subject)
            if iszero(or(iszero(times), iszero(subjectLength))) {
                subject := add(subject, 0x20)
                result := mload(0x40)
                let output := add(result, 0x20)
                for {} 1 {} {
                // Copy the `subject` one word at a time.
                    for { let o := 0 } 1 {} {
                        mstore(add(output, o), mload(add(subject, o)))
                        o := add(o, 0x20)
                        if iszero(lt(o, subjectLength)) { break }
                    }
                    output := add(output, subjectLength)
                    times := sub(times, 1)
                    if iszero(times) { break }
                }
                mstore(output, 0) // Zeroize the slot after the string.
                let resultLength := sub(output, add(result, 0x20))
                mstore(result, resultLength) // Store the length.
            // Allocate the memory.
                mstore(0x40, add(result, add(resultLength, 0x20)))
            }
        }
    }

    /// @dev Returns a copy of `subject` sliced from `start` to `end` (exclusive).
    /// `start` and `end` are byte offsets.
    function slice(string memory subject, uint256 start, uint256 end)
    internal
    pure
    returns (string memory result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            let subjectLength := mload(subject)
            if iszero(gt(subjectLength, end)) { end := subjectLength }
            if iszero(gt(subjectLength, start)) { start := subjectLength }
            if lt(start, end) {
                result := mload(0x40)
                let resultLength := sub(end, start)
                mstore(result, resultLength)
                subject := add(subject, start)
                let w := not(0x1f)
            // Copy the `subject` one word at a time, backwards.
                for { let o := and(add(resultLength, 0x1f), w) } 1 {} {
                    mstore(add(result, o), mload(add(subject, o)))
                    o := add(o, w) // `sub(o, 0x20)`.
                    if iszero(o) { break }
                }
            // Zeroize the slot after the string.
                mstore(add(add(result, 0x20), resultLength), 0)
            // Allocate memory for the length and the bytes,
            // rounded up to a multiple of 32.
                mstore(0x40, add(result, and(add(resultLength, 0x3f), w)))
            }
        }
    }

    /// @dev Returns a copy of `subject` sliced from `start` to the end of the string.
    /// `start` is a byte offset.
    function slice(string memory subject, uint256 start)
    internal
    pure
    returns (string memory result)
    {
        result = slice(subject, start, uint256(int256(-1)));
    }

    /// @dev Returns all the indices of `search` in `subject`.
    /// The indices are byte offsets.
    function indicesOf(string memory subject, string memory search)
    internal
    pure
    returns (uint256[] memory result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            let subjectLength := mload(subject)
            let searchLength := mload(search)

            if iszero(gt(searchLength, subjectLength)) {
                subject := add(subject, 0x20)
                search := add(search, 0x20)
                result := add(mload(0x40), 0x20)

                let subjectStart := subject
                let subjectSearchEnd := add(sub(add(subject, subjectLength), searchLength), 1)
                let h := 0
                if iszero(lt(searchLength, 0x20)) { h := keccak256(search, searchLength) }
                let m := shl(3, sub(0x20, and(searchLength, 0x1f)))
                let s := mload(search)
                for {} 1 {} {
                    let t := mload(subject)
                // Whether the first `searchLength % 32` bytes of
                // `subject` and `search` matches.
                    if iszero(shr(m, xor(t, s))) {
                        if h {
                            if iszero(eq(keccak256(subject, searchLength), h)) {
                                subject := add(subject, 1)
                                if iszero(lt(subject, subjectSearchEnd)) { break }
                                continue
                            }
                        }
                    // Append to `result`.
                        mstore(result, sub(subject, subjectStart))
                        result := add(result, 0x20)
                    // Advance `subject` by `searchLength`.
                        subject := add(subject, searchLength)
                        if searchLength {
                            if iszero(lt(subject, subjectSearchEnd)) { break }
                            continue
                        }
                    }
                    subject := add(subject, 1)
                    if iszero(lt(subject, subjectSearchEnd)) { break }
                }
                let resultEnd := result
            // Assign `result` to the free memory pointer.
                result := mload(0x40)
            // Store the length of `result`.
                mstore(result, shr(5, sub(resultEnd, add(result, 0x20))))
            // Allocate memory for result.
            // We allocate one more word, so this array can be recycled for {split}.
                mstore(0x40, add(resultEnd, 0x20))
            }
        }
    }

    /// @dev Returns a arrays of strings based on the `delimiter` inside of the `subject` string.
    function split(string memory subject, string memory delimiter)
    internal
    pure
    returns (string[] memory result)
    {
        uint256[] memory indices = indicesOf(subject, delimiter);
        /// @solidity memory-safe-assembly
        assembly {
            let w := not(0x1f)
            let indexPtr := add(indices, 0x20)
            let indicesEnd := add(indexPtr, shl(5, add(mload(indices), 1)))
            mstore(add(indicesEnd, w), mload(subject))
            mstore(indices, add(mload(indices), 1))
            let prevIndex := 0
            for {} 1 {} {
                let index := mload(indexPtr)
                mstore(indexPtr, 0x60)
                if iszero(eq(index, prevIndex)) {
                    let element := mload(0x40)
                    let elementLength := sub(index, prevIndex)
                    mstore(element, elementLength)
                // Copy the `subject` one word at a time, backwards.
                    for { let o := and(add(elementLength, 0x1f), w) } 1 {} {
                        mstore(add(element, o), mload(add(add(subject, prevIndex), o)))
                        o := add(o, w) // `sub(o, 0x20)`.
                        if iszero(o) { break }
                    }
                // Zeroize the slot after the string.
                    mstore(add(add(element, 0x20), elementLength), 0)
                // Allocate memory for the length and the bytes,
                // rounded up to a multiple of 32.
                    mstore(0x40, add(element, and(add(elementLength, 0x3f), w)))
                // Store the `element` into the array.
                    mstore(indexPtr, element)
                }
                prevIndex := add(index, mload(delimiter))
                indexPtr := add(indexPtr, 0x20)
                if iszero(lt(indexPtr, indicesEnd)) { break }
            }
            result := indices
            if iszero(mload(delimiter)) {
                result := add(indices, 0x20)
                mstore(result, sub(mload(indices), 2))
            }
        }
    }

    /// @dev Returns a concatenated string of `a` and `b`.
    /// Cheaper than `string.concat()` and does not de-align the free memory pointer.
    function concat(string memory a, string memory b)
    internal
    pure
    returns (string memory result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            let w := not(0x1f)
            result := mload(0x40)
            let aLength := mload(a)
        // Copy `a` one word at a time, backwards.
            for { let o := and(add(aLength, 0x20), w) } 1 {} {
                mstore(add(result, o), mload(add(a, o)))
                o := add(o, w) // `sub(o, 0x20)`.
                if iszero(o) { break }
            }
            let bLength := mload(b)
            let output := add(result, aLength)
        // Copy `b` one word at a time, backwards.
            for { let o := and(add(bLength, 0x20), w) } 1 {} {
                mstore(add(output, o), mload(add(b, o)))
                o := add(o, w) // `sub(o, 0x20)`.
                if iszero(o) { break }
            }
            let totalLength := add(aLength, bLength)
            let last := add(add(result, 0x20), totalLength)
        // Zeroize the slot after the string.
            mstore(last, 0)
        // Stores the length.
            mstore(result, totalLength)
        // Allocate memory for the length and the bytes,
        // rounded up to a multiple of 32.
            mstore(0x40, and(add(last, 0x1f), w))
        }
    }

    /// @dev Returns a copy of the string in either lowercase or UPPERCASE.
    /// WARNING! This function is only compatible with 7-bit ASCII strings.
    function toCase(string memory subject, bool toUpper)
    internal
    pure
    returns (string memory result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            let length := mload(subject)
            if length {
                result := add(mload(0x40), 0x20)
                subject := add(subject, 1)
                let flags := shl(add(70, shl(5, toUpper)), 0x3ffffff)
                let w := not(0)
                for { let o := length } 1 {} {
                    o := add(o, w)
                    let b := and(0xff, mload(add(subject, o)))
                    mstore8(add(result, o), xor(b, and(shr(b, flags), 0x20)))
                    if iszero(o) { break }
                }
                result := mload(0x40)
                mstore(result, length) // Store the length.
                let last := add(add(result, 0x20), length)
                mstore(last, 0) // Zeroize the slot after the string.
                mstore(0x40, add(last, 0x20)) // Allocate the memory.
            }
        }
    }

    /// @dev Returns a string from a small bytes32 string.
    /// `s` must be null-terminated, or behavior will be undefined.
    function fromSmallString(bytes32 s) internal pure returns (string memory result) {
        /// @solidity memory-safe-assembly
        assembly {
            result := mload(0x40)
            let n := 0
            for {} byte(n, s) { n := add(n, 1) } {} // Scan for '\0'.
            mstore(result, n)
            let o := add(result, 0x20)
            mstore(o, s)
            mstore(add(o, n), 0)
            mstore(0x40, add(result, 0x40))
        }
    }

    /// @dev Returns the small string, with all bytes after the first null byte zeroized.
    function normalizeSmallString(bytes32 s) internal pure returns (bytes32 result) {
        /// @solidity memory-safe-assembly
        assembly {
            for {} byte(result, s) { result := add(result, 1) } {} // Scan for '\0'.
            mstore(0x00, s)
            mstore(result, 0x00)
            result := mload(0x00)
        }
    }

    /// @dev Returns the string as a normalized null-terminated small string.
    function toSmallString(string memory s) internal pure returns (bytes32 result) {
        /// @solidity memory-safe-assembly
        assembly {
            result := mload(s)
            if iszero(lt(result, 33)) {
                mstore(0x00, 0xec92f9a3) // `TooBigForSmallString()`.
                revert(0x1c, 0x04)
            }
            result := shl(shl(3, sub(32, result)), mload(add(s, result)))
        }
    }

    /// @dev Returns a lowercased copy of the string.
    /// WARNING! This function is only compatible with 7-bit ASCII strings.
    function lower(string memory subject) internal pure returns (string memory result) {
        result = toCase(subject, false);
    }

    /// @dev Returns an UPPERCASED copy of the string.
    /// WARNING! This function is only compatible with 7-bit ASCII strings.
    function upper(string memory subject) internal pure returns (string memory result) {
        result = toCase(subject, true);
    }

    /// @dev Escapes the string to be used within HTML tags.
    function escapeHTML(string memory s) internal pure returns (string memory result) {
        /// @solidity memory-safe-assembly
        assembly {
            let end := add(s, mload(s))
            result := add(mload(0x40), 0x20)
        // Store the bytes of the packed offsets and strides into the scratch space.
        // `packed = (stride << 5) | offset`. Max offset is 20. Max stride is 6.
            mstore(0x1f, 0x900094)
            mstore(0x08, 0xc0000000a6ab)
        // Store "&quot;&amp;&#39;&lt;&gt;" into the scratch space.
            mstore(0x00, shl(64, 0x2671756f743b26616d703b262333393b266c743b2667743b))
            for {} iszero(eq(s, end)) {} {
                s := add(s, 1)
                let c := and(mload(s), 0xff)
            // Not in `["\"","'","&","<",">"]`.
                if iszero(and(shl(c, 1), 0x500000c400000000)) {
                    mstore8(result, c)
                    result := add(result, 1)
                    continue
                }
                let t := shr(248, mload(c))
                mstore(result, mload(and(t, 0x1f)))
                result := add(result, shr(5, t))
            }
            let last := result
            mstore(last, 0) // Zeroize the slot after the string.
            result := mload(0x40)
            mstore(result, sub(last, add(result, 0x20))) // Store the length.
            mstore(0x40, add(last, 0x20)) // Allocate the memory.
        }
    }

    /// @dev Escapes the string to be used within double-quotes in a JSON.
    /// If `addDoubleQuotes` is true, the result will be enclosed in double-quotes.
    function escapeJSON(string memory s, bool addDoubleQuotes)
    internal
    pure
    returns (string memory result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            let end := add(s, mload(s))
            result := add(mload(0x40), 0x20)
            if addDoubleQuotes {
                mstore8(result, 34)
                result := add(1, result)
            }
        // Store "\\u0000" in scratch space.
        // Store "0123456789abcdef" in scratch space.
        // Also, store `{0x08:"b", 0x09:"t", 0x0a:"n", 0x0c:"f", 0x0d:"r"}`.
        // into the scratch space.
            mstore(0x15, 0x5c75303030303031323334353637383961626364656662746e006672)
        // Bitmask for detecting `["\"","\\"]`.
            let e := or(shl(0x22, 1), shl(0x5c, 1))
            for {} iszero(eq(s, end)) {} {
                s := add(s, 1)
                let c := and(mload(s), 0xff)
                if iszero(lt(c, 0x20)) {
                    if iszero(and(shl(c, 1), e)) {
                    // Not in `["\"","\\"]`.
                        mstore8(result, c)
                        result := add(result, 1)
                        continue
                    }
                    mstore8(result, 0x5c) // "\\".
                    mstore8(add(result, 1), c)
                    result := add(result, 2)
                    continue
                }
                if iszero(and(shl(c, 1), 0x3700)) {
                // Not in `["\b","\t","\n","\f","\d"]`.
                    mstore8(0x1d, mload(shr(4, c))) // Hex value.
                    mstore8(0x1e, mload(and(c, 15))) // Hex value.
                    mstore(result, mload(0x19)) // "\\u00XX".
                    result := add(result, 6)
                    continue
                }
                mstore8(result, 0x5c) // "\\".
                mstore8(add(result, 1), mload(add(c, 8)))
                result := add(result, 2)
            }
            if addDoubleQuotes {
                mstore8(result, 34)
                result := add(1, result)
            }
            let last := result
            mstore(last, 0) // Zeroize the slot after the string.
            result := mload(0x40)
            mstore(result, sub(last, add(result, 0x20))) // Store the length.
            mstore(0x40, add(last, 0x20)) // Allocate the memory.
        }
    }

    /// @dev Escapes the string to be used within double-quotes in a JSON.
    function escapeJSON(string memory s) internal pure returns (string memory result) {
        result = escapeJSON(s, false);
    }

    /// @dev Returns whether `a` equals `b`.
    function eq(string memory a, string memory b) internal pure returns (bool result) {
        /// @solidity memory-safe-assembly
        assembly {
            result := eq(keccak256(add(a, 0x20), mload(a)), keccak256(add(b, 0x20), mload(b)))
        }
    }

    /// @dev Returns whether `a` equals `b`, where `b` is a null-terminated small string.
    function eqs(string memory a, bytes32 b) internal pure returns (bool result) {
        /// @solidity memory-safe-assembly
        assembly {
        // These should be evaluated on compile time, as far as possible.
            let m := not(shl(7, div(not(iszero(b)), 255))) // `0x7f7f ...`.
            let x := not(or(m, or(b, add(m, and(b, m)))))
            let r := shl(7, iszero(iszero(shr(128, x))))
            r := or(r, shl(6, iszero(iszero(shr(64, shr(r, x))))))
            r := or(r, shl(5, lt(0xffffffff, shr(r, x))))
            r := or(r, shl(4, lt(0xffff, shr(r, x))))
            r := or(r, shl(3, lt(0xff, shr(r, x))))
        // forgefmt: disable-next-item
            result := gt(eq(mload(a), add(iszero(x), xor(31, shr(3, r)))),
                xor(shr(add(8, r), b), shr(add(8, r), mload(add(a, 0x20)))))
        }
    }

    /// @dev Packs a single string with its length into a single word.
    /// Returns `bytes32(0)` if the length is zero or greater than 31.
    function packOne(string memory a) internal pure returns (bytes32 result) {
        /// @solidity memory-safe-assembly
        assembly {
        // We don't need to zero right pad the string,
        // since this is our own custom non-standard packing scheme.
            result :=
            mul(
            // Load the length and the bytes.
                mload(add(a, 0x1f)),
            // `length != 0 && length < 32`. Abuses underflow.
            // Assumes that the length is valid and within the block gas limit.
                lt(sub(mload(a), 1), 0x1f)
            )
        }
    }

    /// @dev Unpacks a string packed using {packOne}.
    /// Returns the empty string if `packed` is `bytes32(0)`.
    /// If `packed` is not an output of {packOne}, the output behavior is undefined.
    function unpackOne(bytes32 packed) internal pure returns (string memory result) {
        /// @solidity memory-safe-assembly
        assembly {
        // Grab the free memory pointer.
            result := mload(0x40)
        // Allocate 2 words (1 for the length, 1 for the bytes).
            mstore(0x40, add(result, 0x40))
        // Zeroize the length slot.
            mstore(result, 0)
        // Store the length and bytes.
            mstore(add(result, 0x1f), packed)
        // Right pad with zeroes.
            mstore(add(add(result, 0x20), mload(result)), 0)
        }
    }

    /// @dev Packs two strings with their lengths into a single word.
    /// Returns `bytes32(0)` if combined length is zero or greater than 30.
    function packTwo(string memory a, string memory b) internal pure returns (bytes32 result) {
        /// @solidity memory-safe-assembly
        assembly {
            let aLength := mload(a)
        // We don't need to zero right pad the strings,
        // since this is our own custom non-standard packing scheme.
            result :=
            mul(
            // Load the length and the bytes of `a` and `b`.
                or(
                    shl(shl(3, sub(0x1f, aLength)), mload(add(a, aLength))),
                    mload(sub(add(b, 0x1e), aLength))
                ),
            // `totalLength != 0 && totalLength < 31`. Abuses underflow.
            // Assumes that the lengths are valid and within the block gas limit.
                lt(sub(add(aLength, mload(b)), 1), 0x1e)
            )
        }
    }

    /// @dev Unpacks strings packed using {packTwo}.
    /// Returns the empty strings if `packed` is `bytes32(0)`.
    /// If `packed` is not an output of {packTwo}, the output behavior is undefined.
    function unpackTwo(bytes32 packed)
    internal
    pure
    returns (string memory resultA, string memory resultB)
    {
        /// @solidity memory-safe-assembly
        assembly {
        // Grab the free memory pointer.
            resultA := mload(0x40)
            resultB := add(resultA, 0x40)
        // Allocate 2 words for each string (1 for the length, 1 for the byte). Total 4 words.
            mstore(0x40, add(resultB, 0x40))
        // Zeroize the length slots.
            mstore(resultA, 0)
            mstore(resultB, 0)
        // Store the lengths and bytes.
            mstore(add(resultA, 0x1f), packed)
            mstore(add(resultB, 0x1f), mload(add(add(resultA, 0x20), mload(resultA))))
        // Right pad with zeroes.
            mstore(add(add(resultA, 0x20), mload(resultA)), 0)
            mstore(add(add(resultB, 0x20), mload(resultB)), 0)
        }
    }

    /// @dev Directly returns `a` without copying.
    function directReturn(string memory a) internal pure {
        assembly {
        // Assumes that the string does not start from the scratch space.
            let retStart := sub(a, 0x20)
            let retSize := add(mload(a), 0x40)
        // Right pad with zeroes. Just in case the string is produced
        // by a method that doesn't zero right pad.
            mstore(add(retStart, retSize), 0)
        // Store the return offset.
            mstore(retStart, 0x20)
        // End the transaction, returning the string.
            return(retStart, retSize)
        }
    }
}

/// @notice Simple single owner authorization mixin.
/// @author Solady (https://github.com/vectorized/solady/blob/main/src/auth/Ownable.sol)
///
/// @dev Note:
/// This implementation does NOT auto-initialize the owner to `msg.sender`.
/// You MUST call the `_initializeOwner` in the constructor / initializer.
///
/// While the ownable portion follows
/// [EIP-173](https://eips.ethereum.org/EIPS/eip-173) for compatibility,
/// the nomenclature for the 2-step ownership handover may be unique to this codebase.
abstract contract Ownable {
    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                       CUSTOM ERRORS                        */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev The caller is not authorized to call the function.
    error Unauthorized();

    /// @dev The `newOwner` cannot be the zero address.
    error NewOwnerIsZeroAddress();

    /// @dev The `pendingOwner` does not have a valid handover request.
    error NoHandoverRequest();

    /// @dev Cannot double-initialize.
    error AlreadyInitialized();

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                           EVENTS                           */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev The ownership is transferred from `oldOwner` to `newOwner`.
    /// This event is intentionally kept the same as OpenZeppelin's Ownable to be
    /// compatible with indexers and [EIP-173](https://eips.ethereum.org/EIPS/eip-173),
    /// despite it not being as lightweight as a single argument event.
    event OwnershipTransferred(address indexed oldOwner, address indexed newOwner);

    /// @dev An ownership handover to `pendingOwner` has been requested.
    event OwnershipHandoverRequested(address indexed pendingOwner);

    /// @dev The ownership handover to `pendingOwner` has been canceled.
    event OwnershipHandoverCanceled(address indexed pendingOwner);

    /// @dev `keccak256(bytes("OwnershipTransferred(address,address)"))`.
    uint256 private constant _OWNERSHIP_TRANSFERRED_EVENT_SIGNATURE =
    0x8be0079c531659141344cd1fd0a4f28419497f9722a3daafe3b4186f6b6457e0;

    /// @dev `keccak256(bytes("OwnershipHandoverRequested(address)"))`.
    uint256 private constant _OWNERSHIP_HANDOVER_REQUESTED_EVENT_SIGNATURE =
    0xdbf36a107da19e49527a7176a1babf963b4b0ff8cde35ee35d6cd8f1f9ac7e1d;

    /// @dev `keccak256(bytes("OwnershipHandoverCanceled(address)"))`.
    uint256 private constant _OWNERSHIP_HANDOVER_CANCELED_EVENT_SIGNATURE =
    0xfa7b8eab7da67f412cc9575ed43464468f9bfbae89d1675917346ca6d8fe3c92;

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                          STORAGE                           */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev The owner slot is given by:
    /// `bytes32(~uint256(uint32(bytes4(keccak256("_OWNER_SLOT_NOT")))))`.
    /// It is intentionally chosen to be a high value
    /// to avoid collision with lower slots.
    /// The choice of manual storage layout is to enable compatibility
    /// with both regular and upgradeable contracts.
    bytes32 internal constant _OWNER_SLOT =
    0xffffffffffffffffffffffffffffffffffffffffffffffffffffffff74873927;

    /// The ownership handover slot of `newOwner` is given by:
    /// ```
    ///     mstore(0x00, or(shl(96, user), _HANDOVER_SLOT_SEED))
    ///     let handoverSlot := keccak256(0x00, 0x20)
    /// ```
    /// It stores the expiry timestamp of the two-step ownership handover.
    uint256 private constant _HANDOVER_SLOT_SEED = 0x389a75e1;

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                     INTERNAL FUNCTIONS                     */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Override to return true to make `_initializeOwner` prevent double-initialization.
    function _guardInitializeOwner() internal pure virtual returns (bool guard) {}

    /// @dev Initializes the owner directly without authorization guard.
    /// This function must be called upon initialization,
    /// regardless of whether the contract is upgradeable or not.
    /// This is to enable generalization to both regular and upgradeable contracts,
    /// and to save gas in case the initial owner is not the caller.
    /// For performance reasons, this function will not check if there
    /// is an existing owner.
    function _initializeOwner(address newOwner) internal virtual {
        if (_guardInitializeOwner()) {
            /// @solidity memory-safe-assembly
            assembly {
                let ownerSlot := _OWNER_SLOT
                if sload(ownerSlot) {
                    mstore(0x00, 0x0dc149f0) // `AlreadyInitialized()`.
                    revert(0x1c, 0x04)
                }
            // Clean the upper 96 bits.
                newOwner := shr(96, shl(96, newOwner))
            // Store the new value.
                sstore(ownerSlot, or(newOwner, shl(255, iszero(newOwner))))
            // Emit the {OwnershipTransferred} event.
                log3(0, 0, _OWNERSHIP_TRANSFERRED_EVENT_SIGNATURE, 0, newOwner)
            }
        } else {
            /// @solidity memory-safe-assembly
            assembly {
            // Clean the upper 96 bits.
                newOwner := shr(96, shl(96, newOwner))
            // Store the new value.
                sstore(_OWNER_SLOT, newOwner)
            // Emit the {OwnershipTransferred} event.
                log3(0, 0, _OWNERSHIP_TRANSFERRED_EVENT_SIGNATURE, 0, newOwner)
            }
        }
    }

    /// @dev Sets the owner directly without authorization guard.
    function _setOwner(address newOwner) internal virtual {
        if (_guardInitializeOwner()) {
            /// @solidity memory-safe-assembly
            assembly {
                let ownerSlot := _OWNER_SLOT
            // Clean the upper 96 bits.
                newOwner := shr(96, shl(96, newOwner))
            // Emit the {OwnershipTransferred} event.
                log3(0, 0, _OWNERSHIP_TRANSFERRED_EVENT_SIGNATURE, sload(ownerSlot), newOwner)
            // Store the new value.
                sstore(ownerSlot, or(newOwner, shl(255, iszero(newOwner))))
            }
        } else {
            /// @solidity memory-safe-assembly
            assembly {
                let ownerSlot := _OWNER_SLOT
            // Clean the upper 96 bits.
                newOwner := shr(96, shl(96, newOwner))
            // Emit the {OwnershipTransferred} event.
                log3(0, 0, _OWNERSHIP_TRANSFERRED_EVENT_SIGNATURE, sload(ownerSlot), newOwner)
            // Store the new value.
                sstore(ownerSlot, newOwner)
            }
        }
    }

    /// @dev Throws if the sender is not the owner.
    function _checkOwner() internal view virtual {
        /// @solidity memory-safe-assembly
        assembly {
        // If the caller is not the stored owner, revert.
            if iszero(eq(caller(), sload(_OWNER_SLOT))) {
                mstore(0x00, 0x82b42900) // `Unauthorized()`.
                revert(0x1c, 0x04)
            }
        }
    }

    /// @dev Returns how long a two-step ownership handover is valid for in seconds.
    /// Override to return a different value if needed.
    /// Made internal to conserve bytecode. Wrap it in a public function if needed.
    function _ownershipHandoverValidFor() internal view virtual returns (uint64) {
        return 48 * 3600;
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                  PUBLIC UPDATE FUNCTIONS                   */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Allows the owner to transfer the ownership to `newOwner`.
    function transferOwnership(address newOwner) public payable virtual onlyOwner {
        /// @solidity memory-safe-assembly
        assembly {
            if iszero(shl(96, newOwner)) {
                mstore(0x00, 0x7448fbae) // `NewOwnerIsZeroAddress()`.
                revert(0x1c, 0x04)
            }
        }
        _setOwner(newOwner);
    }

    /// @dev Allows the owner to renounce their ownership.
    function renounceOwnership() public payable virtual onlyOwner {
        _setOwner(address(0));
    }

    /// @dev Request a two-step ownership handover to the caller.
    /// The request will automatically expire in 48 hours (172800 seconds) by default.
    function requestOwnershipHandover() public payable virtual {
        unchecked {
            uint256 expires = block.timestamp + _ownershipHandoverValidFor();
        /// @solidity memory-safe-assembly
            assembly {
            // Compute and set the handover slot to `expires`.
                mstore(0x0c, _HANDOVER_SLOT_SEED)
                mstore(0x00, caller())
                sstore(keccak256(0x0c, 0x20), expires)
            // Emit the {OwnershipHandoverRequested} event.
                log2(0, 0, _OWNERSHIP_HANDOVER_REQUESTED_EVENT_SIGNATURE, caller())
            }
        }
    }

    /// @dev Cancels the two-step ownership handover to the caller, if any.
    function cancelOwnershipHandover() public payable virtual {
        /// @solidity memory-safe-assembly
        assembly {
        // Compute and set the handover slot to 0.
            mstore(0x0c, _HANDOVER_SLOT_SEED)
            mstore(0x00, caller())
            sstore(keccak256(0x0c, 0x20), 0)
        // Emit the {OwnershipHandoverCanceled} event.
            log2(0, 0, _OWNERSHIP_HANDOVER_CANCELED_EVENT_SIGNATURE, caller())
        }
    }

    /// @dev Allows the owner to complete the two-step ownership handover to `pendingOwner`.
    /// Reverts if there is no existing ownership handover requested by `pendingOwner`.
    function completeOwnershipHandover(address pendingOwner) public payable virtual onlyOwner {
        /// @solidity memory-safe-assembly
        assembly {
        // Compute and set the handover slot to 0.
            mstore(0x0c, _HANDOVER_SLOT_SEED)
            mstore(0x00, pendingOwner)
            let handoverSlot := keccak256(0x0c, 0x20)
        // If the handover does not exist, or has expired.
            if gt(timestamp(), sload(handoverSlot)) {
                mstore(0x00, 0x6f5e8818) // `NoHandoverRequest()`.
                revert(0x1c, 0x04)
            }
        // Set the handover slot to 0.
            sstore(handoverSlot, 0)
        }
        _setOwner(pendingOwner);
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                   PUBLIC READ FUNCTIONS                    */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Returns the owner of the contract.
    function owner() public view virtual returns (address result) {
        /// @solidity memory-safe-assembly
        assembly {
            result := sload(_OWNER_SLOT)
        }
    }

    /// @dev Returns the expiry timestamp for the two-step ownership handover to `pendingOwner`.
    function ownershipHandoverExpiresAt(address pendingOwner)
    public
    view
    virtual
    returns (uint256 result)
    {
        /// @solidity memory-safe-assembly
        assembly {
        // Compute the handover slot.
            mstore(0x0c, _HANDOVER_SLOT_SEED)
            mstore(0x00, pendingOwner)
        // Load the handover slot.
            result := sload(keccak256(0x0c, 0x20))
        }
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                         MODIFIERS                          */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Marks a function as only callable by the owner.
    modifier onlyOwner() virtual {
        _checkOwner();
        _;
    }
}


/// @title ERC_YB_NFT
/// @notice ERC_YB_NFT provides an interface for interacting with the
/// NFT tokens in a DN404 implementation.
///
/// @author vectorized.eth (@optimizoor)
/// @author Quit (@0xQuit)
/// @author Michael Amadi (@AmadiMichaels)
/// @author cygaar (@0xCygaar)
/// @author Thomas (@0xjustadev)
/// @author Harrison (@PopPunkOnChain)
///
/// @dev Note:
/// - The ERC721 data is stored in the base DN404 contract.
contract ERC_YB_NFT {
    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                           EVENTS                           */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Emitted when token `id` is transferred from `from` to `to`.
    event Transfer(address indexed from, address indexed to, uint256 indexed id);

    /// @dev Emitted when `owner` enables `account` to manage the `id` token.
    event Approval(address indexed owner, address indexed account, uint256 indexed id);

    /// @dev Emitted when `owner` enables or disables `operator` to manage all of their tokens.
    event ApprovalForAll(address indexed owner, address indexed operator, bool isApproved);

    /// @dev The ownership is transferred from `oldOwner` to `newOwner`.
    /// This is for marketplace signaling purposes. This contract has a `pullOwner()`
    /// function that will sync the owner from the base contract.
    event OwnershipTransferred(address indexed oldOwner, address indexed newOwner);

    /// @dev `keccak256(bytes("Transfer(address,address,uint256)"))`.
    uint256 private constant _TRANSFER_EVENT_SIGNATURE =
    0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef;

    /// @dev `keccak256(bytes("Approval(address,address,uint256)"))`.
    uint256 private constant _APPROVAL_EVENT_SIGNATURE =
    0x8c5be1e5ebec7d5bd14f71427d1e84f3dd0314c0f7b2291e5b200ac8c7c3b925;

    /// @dev `keccak256(bytes("ApprovalForAll(address,address,bool)"))`.
    uint256 private constant _APPROVAL_FOR_ALL_EVENT_SIGNATURE =
    0x17307eab39ab6107e8899845ad3d59bd9653f200f220920489ca2b5937696c31;

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                        CUSTOM ERRORS                       */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Thrown when a call for an NFT function did not originate
    /// from the base DN404 contract.
    error SenderNotBase();

    /// @dev Thrown when a call for an NFT function did not originate from the deployer.
    error SenderNotDeployer();

    /// @dev Thrown when transferring an NFT to a contract address that
    /// does not implement ERC721Receiver.
    error TransferToNonERC721ReceiverImplementer();

    /// @dev Thrown when linking to the DN404 base contract and the
    /// DN404 supportsInterface check fails or the call reverts.
    error CannotLink();

    /// @dev Thrown when a linkMirrorContract call is received and the
    /// NFT mirror contract has already been linked to a DN404 base contract.
    error AlreadyLinked();

    /// @dev Thrown when retrieving the base DN404 address when a link has not
    /// been established.
    error NotLinked();

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                          STORAGE                           */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Struct contain the NFT mirror contract storage.
    struct DN404NFTStorage {
        address baseERC20;
        address deployer;
        address owner;
    }

    /// @dev Returns a storage pointer for DN404NFTStorage.
    function _getDN404NFTStorage() internal pure virtual returns (DN404NFTStorage storage $) {
        /// @solidity memory-safe-assembly
        assembly {
        // `uint72(bytes9(keccak256("DN404_MIRROR_STORAGE")))`.
            $.slot := 0x3602298b8c10b01230 // Truncate to 9 bytes to reduce bytecode size.
        }
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                        CONSTRUCTOR                         */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    constructor(address deployer) {
        // For non-proxies, we will store the deployer so that only the deployer can
        // link the base contract.
        _getDN404NFTStorage().deployer = deployer;
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                     ERC721 OPERATIONS                      */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Returns the token collection name from the base DN404 contract.
    function name() public view virtual returns (string memory result) {
        return _readString(0x06fdde03, 0); // `symbol()`.
    }

    /// @dev Returns the token collection symbol from the base DN404 contract.
    function symbol() public view virtual returns (string memory result) {
        return _readString(0x95d89b41, 0); // `symbol()`.
    }

    /// @dev Returns the Uniform Resource Identifier (URI) for token `id` from
    /// the base DN404 contract.
    function tokenURI(uint256 id) public view virtual returns (string memory result) {
        return _readString(0xc87b56dd, id); // `tokenURI()`.
    }

    /// @dev Returns the total NFT supply from the base DN404 contract.
    function totalSupply() public view virtual returns (uint256 result) {
        return _readWord(0xe2c79281, 0, 0); // `totalNFTSupply()`.
    }

    /// @dev Returns the number of NFT tokens owned by `nftOwner` from the base DN404 contract.
    ///
    /// Requirements:
    /// - `nftOwner` must not be the zero address.
    function balanceOf(address nftOwner) public view virtual returns (uint256 result) {
        return _readWord(0xf5b100ea, uint160(nftOwner), 0); // `balanceOfNFT(address)`.
    }

    /// @dev Returns the owner of token `id` from the base DN404 contract.
    ///
    /// Requirements:
    /// - Token `id` must exist.
    function ownerOf(uint256 id) public view virtual returns (address result) {
        return address(uint160(_readWord(0x6352211e, id, 0))); // `ownerOf(uint256)`.
    }

    /// @dev Returns the owner of token `id` from the base DN404 contract.
    /// Returns `address(0)` instead of reverting if the token does not exist.
    function ownerAt(uint256 id) public view virtual returns (address result) {
        return address(uint160(_readWord(0x24359879, id, 0))); // `ownerAt(uint256)`.
    }

    /// @dev Sets `spender` as the approved account to manage token `id` in
    /// the base DN404 contract.
    ///
    /// Requirements:
    /// - Token `id` must exist.
    /// - The caller must be the owner of the token,
    ///   or an approved operator for the token owner.
    ///
    /// Emits an {Approval} event.
    function approve(address spender, uint256 id) public virtual {
        address base = baseERC20();
        /// @solidity memory-safe-assembly
        assembly {
            spender := shr(96, shl(96, spender))
            let m := mload(0x40)
            mstore(0x00, 0xd10b6e0c) // `approveNFT(address,uint256,address)`.
            mstore(0x20, spender)
            mstore(0x40, id)
            mstore(0x60, caller())
            if iszero(
                and(
                    gt(returndatasize(), 0x1f),
                    call(gas(), base, callvalue(), 0x1c, 0x64, 0x00, 0x20)
                )
            ) {
                returndatacopy(m, 0x00, returndatasize())
                revert(m, returndatasize())
            }
            mstore(0x40, m) // Restore the free memory pointer.
            mstore(0x60, 0) // Restore the zero pointer.
        // Emit the {Approval} event.
            log4(codesize(), 0x00, _APPROVAL_EVENT_SIGNATURE, shr(96, mload(0x0c)), spender, id)
        }
    }

    /// @dev Returns the account approved to manage token `id` from
    /// the base DN404 contract.
    ///
    /// Requirements:
    /// - Token `id` must exist.
    function getApproved(uint256 id) public view virtual returns (address) {
        return address(uint160(_readWord(0x081812fc, id, 0))); // `getApproved(uint256)`.
    }

    /// @dev Sets whether `operator` is approved to manage the tokens of the caller in
    /// the base DN404 contract.
    ///
    /// Emits an {ApprovalForAll} event.
    function setApprovalForAll(address operator, bool approved) public virtual {
        address base = baseERC20();
        /// @solidity memory-safe-assembly
        assembly {
            operator := shr(96, shl(96, operator))
            let m := mload(0x40)
            mstore(0x00, 0x813500fc) // `setApprovalForAll(address,bool,address)`.
            mstore(0x20, operator)
            mstore(0x40, iszero(iszero(approved)))
            mstore(0x60, caller())
            if iszero(
                and(eq(mload(0x00), 1), call(gas(), base, callvalue(), 0x1c, 0x64, 0x00, 0x20))
            ) {
                returndatacopy(m, 0x00, returndatasize())
                revert(m, returndatasize())
            }
        // Emit the {ApprovalForAll} event.
        // The `approved` value is already at 0x40.
            log3(0x40, 0x20, _APPROVAL_FOR_ALL_EVENT_SIGNATURE, caller(), operator)
            mstore(0x40, m) // Restore the free memory pointer.
            mstore(0x60, 0) // Restore the zero pointer.
        }
    }

    /// @dev Returns whether `operator` is approved to manage the tokens of `nftOwner` from
    /// the base DN404 contract.
    function isApprovedForAll(address nftOwner, address operator)
    public
    view
    virtual
    returns (bool result)
    {
        // `isApprovedForAll(address,address)`.
        return _readWord(0xe985e9c5, uint160(nftOwner), uint160(operator)) != 0;
    }

    /// @dev Transfers token `id` from `from` to `to`.
    ///
    /// Requirements:
    ///
    /// - Token `id` must exist.
    /// - `from` must be the owner of the token.
    /// - `to` cannot be the zero address.
    /// - The caller must be the owner of the token, or be approved to manage the token.
    ///
    /// Emits a {Transfer} event.
    function transferFrom(address from, address to, uint256 id) public virtual {
        address base = baseERC20();
        /// @solidity memory-safe-assembly
        assembly {
            from := shr(96, shl(96, from))
            to := shr(96, shl(96, to))
            let m := mload(0x40)
            mstore(m, 0xe5eb36c8) // `transferFromNFT(address,address,uint256,address)`.
            mstore(add(m, 0x20), from)
            mstore(add(m, 0x40), to)
            mstore(add(m, 0x60), id)
            mstore(add(m, 0x80), caller())
            if iszero(
                and(eq(mload(m), 1), call(gas(), base, callvalue(), add(m, 0x1c), 0x84, m, 0x20))
            ) {
                returndatacopy(m, 0x00, returndatasize())
                revert(m, returndatasize())
            }
        // Emit the {Transfer} event.
            log4(codesize(), 0x00, _TRANSFER_EVENT_SIGNATURE, from, to, id)
        }
    }

    /// @dev Equivalent to `safeTransferFrom(from, to, id, "")`.
    function safeTransferFrom(address from, address to, uint256 id) public payable virtual {
        transferFrom(from, to, id);

        if (_hasCode(to)) _checkOnERC721Received(from, to, id, "");
    }

    /// @dev Transfers token `id` from `from` to `to`.
    ///
    /// Requirements:
    ///
    /// - Token `id` must exist.
    /// - `from` must be the owner of the token.
    /// - `to` cannot be the zero address.
    /// - The caller must be the owner of the token, or be approved to manage the token.
    /// - If `to` refers to a smart contract, it must implement
    ///   {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
    ///
    /// Emits a {Transfer} event.
    function safeTransferFrom(address from, address to, uint256 id, bytes calldata data)
    public
    virtual
    {
        transferFrom(from, to, id);

        if (_hasCode(to)) _checkOnERC721Received(from, to, id, data);
    }

    /// @dev Returns true if this contract implements the interface defined by `interfaceId`.
    /// See: https://eips.ethereum.org/EIPS/eip-165
    /// This function call must use less than 30000 gas.
    function supportsInterface(bytes4 interfaceId) public view virtual returns (bool result) {
        /// @solidity memory-safe-assembly
        assembly {
            let s := shr(224, interfaceId)
        // ERC165: 0x01ffc9a7, ERC721: 0x80ac58cd, ERC721Metadata: 0x5b5e139f.
            result := or(or(eq(s, 0x01ffc9a7), eq(s, 0x80ac58cd)), eq(s, 0x5b5e139f))
        }
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                  OWNER SYNCING OPERATIONS                  */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Returns the `owner` of the contract, for marketplace signaling purposes.
    function owner() public view virtual returns (address) {
        return _getDN404NFTStorage().owner;
    }

    /// @dev Permissionless function to pull the owner from the base DN404 contract
    /// if it implements ownable, for marketplace signaling purposes.
    function pullOwner() public virtual {
        address newOwner;
        address base = baseERC20();
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x00, 0x8da5cb5b) // `owner()`.
            if and(gt(returndatasize(), 0x1f), staticcall(gas(), base, 0x1c, 0x04, 0x00, 0x20)) {
                newOwner := shr(96, mload(0x0c))
            }
        }
        DN404NFTStorage storage $ = _getDN404NFTStorage();
        address oldOwner = $.owner;
        if (oldOwner != newOwner) {
            $.owner = newOwner;
            emit OwnershipTransferred(oldOwner, newOwner);
        }
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                     MIRROR OPERATIONS                      */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Returns the address of the base DN404 contract.
    function baseERC20() public view virtual returns (address base) {
        base = _getDN404NFTStorage().baseERC20;
        if (base == address(0)) revert NotLinked();
    }

    /// @dev Fallback modifier to execute calls from the base DN404 contract.
    modifier dn404NFTFallback() virtual {
        DN404NFTStorage storage $ = _getDN404NFTStorage();

        uint256 fnSelector = _calldataload(0x00) >> 224;

        // `logTransfer(uint256[])`.
        if (fnSelector == 0x263c69d6) {
            if (msg.sender != $.baseERC20) revert SenderNotBase();
            /// @solidity memory-safe-assembly
            assembly {
            // When returndatacopy copies 1 or more out-of-bounds bytes, it reverts.
                returndatacopy(0x00, returndatasize(), lt(calldatasize(), 0x20))
                let o := add(0x24, calldataload(0x04)) // Packed logs offset.
                returndatacopy(0x00, returndatasize(), lt(calldatasize(), o))
                let end := add(o, shl(5, calldataload(sub(o, 0x20))))
                returndatacopy(0x00, returndatasize(), lt(calldatasize(), end))

                for {} iszero(eq(o, end)) { o := add(0x20, o) } {
                    let d := calldataload(o) // Entry in the packed logs.
                    let a := shr(96, d) // The address.
                    let b := and(1, d) // Whether it is a burn.
                    log4(
                        codesize(),
                        0x00,
                        _TRANSFER_EVENT_SIGNATURE,
                        mul(a, b), // `from`.
                        mul(a, iszero(b)), // `to`.
                        shr(168, shl(160, d)) // `id`.
                    )
                }
                mstore(0x00, 0x01)
                return(0x00, 0x20)
            }
        }
        // `linkMirrorContract(address)`.
        if (fnSelector == 0x0f4599e5) {
            if ($.deployer != address(0)) {
                if (address(uint160(_calldataload(0x04))) != $.deployer) {
                    revert SenderNotDeployer();
                }
            }
            if ($.baseERC20 != address(0)) revert AlreadyLinked();
            $.baseERC20 = msg.sender;
            /// @solidity memory-safe-assembly
            assembly {
                mstore(0x00, 0x01)
                return(0x00, 0x20)
            }
        }
        _;
    }

    /// @dev Fallback function for calls from base DN404 contract.
    fallback() external payable virtual dn404NFTFallback {}

    receive() external payable virtual {}

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                      PRIVATE HELPERS                       */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Helper to read a string from the base DN404 contract.
    function _readString(uint256 fnSelector, uint256 arg0)
    private
    view
    returns (string memory result)
    {
        address base = baseERC20();
        /// @solidity memory-safe-assembly
        assembly {
            result := mload(0x40)
            mstore(0x00, fnSelector)
            mstore(0x20, arg0)
            if iszero(staticcall(gas(), base, 0x1c, 0x24, 0x00, 0x00)) {
                returndatacopy(result, 0x00, returndatasize())
                revert(result, returndatasize())
            }
            returndatacopy(0x00, 0x00, 0x20) // Copy the offset of the string in returndata.
            returndatacopy(result, mload(0x00), 0x20) // Copy the length of the string.
            returndatacopy(add(result, 0x20), add(mload(0x00), 0x20), mload(result)) // Copy the string.
            mstore(0x40, add(add(result, 0x20), mload(result))) // Allocate memory.
        }
    }

    /// @dev Helper to read a word from the base DN404 contract.
    function _readWord(uint256 fnSelector, uint256 arg0, uint256 arg1)
    private
    view
    returns (uint256 result)
    {
        address base = baseERC20();
        /// @solidity memory-safe-assembly
        assembly {
            let m := mload(0x40)
            mstore(0x00, fnSelector)
            mstore(0x20, arg0)
            mstore(0x40, arg1)
            if iszero(
                and(gt(returndatasize(), 0x1f), staticcall(gas(), base, 0x1c, 0x44, 0x00, 0x20))
            ) {
                returndatacopy(m, 0x00, returndatasize())
                revert(m, returndatasize())
            }
            mstore(0x40, m) // Restore the free memory pointer.
            result := mload(0x00)
        }
    }

    /// @dev Returns the calldata value at `offset`.
    function _calldataload(uint256 offset) private pure returns (uint256 value) {
        /// @solidity memory-safe-assembly
        assembly {
            value := calldataload(offset)
        }
    }

    /// @dev Returns if `a` has bytecode of non-zero length.
    function _hasCode(address a) private view returns (bool result) {
        /// @solidity memory-safe-assembly
        assembly {
            result := extcodesize(a) // Can handle dirty upper bits.
        }
    }

    /// @dev Perform a call to invoke {IERC721Receiver-onERC721Received} on `to`.
    /// Reverts if the target does not support the function correctly.
    function _checkOnERC721Received(address from, address to, uint256 id, bytes memory data)
    private
    {
        /// @solidity memory-safe-assembly
        assembly {
        // Prepare the calldata.
            let m := mload(0x40)
            let onERC721ReceivedSelector := 0x150b7a02
            mstore(m, onERC721ReceivedSelector)
            mstore(add(m, 0x20), caller()) // The `operator`, which is always `msg.sender`.
            mstore(add(m, 0x40), shr(96, shl(96, from)))
            mstore(add(m, 0x60), id)
            mstore(add(m, 0x80), 0x80)
            let n := mload(data)
            mstore(add(m, 0xa0), n)
            if n { pop(staticcall(gas(), 4, add(data, 0x20), n, add(m, 0xc0), n)) }
        // Revert if the call reverts.
            if iszero(call(gas(), to, 0, add(m, 0x1c), add(n, 0xa4), m, 0x20)) {
                if returndatasize() {
                // Bubble up the revert if the call reverts.
                    returndatacopy(m, 0x00, returndatasize())
                    revert(m, returndatasize())
                }
            }
        // Load the returndata and compare it.
            if iszero(eq(mload(m), shl(224, onERC721ReceivedSelector))) {
                mstore(0x00, 0xd1a57ed6) // `TransferToNonERC721ReceiverImplementer()`.
                revert(0x1c, 0x04)
            }
        }
    }
}

/// @title DN404
/// @notice DN404 is a hybrid ERC20 and ERC721 implementation that mints
/// and burns NFTs based on an account's ERC20 token balance.
///
/// @author vectorized.eth (@optimizoor)
/// @author Quit (@0xQuit)
/// @author Michael Amadi (@AmadiMichaels)
/// @author cygaar (@0xCygaar)
/// @author Thomas (@0xjustadev)
/// @author Harrison (@PopPunkOnChain)
///
/// @dev Note:
/// - The ERC721 data is stored in this base DN404 contract, however a
///   ERC_YB_NFT contract ***MUST*** be deployed and linked during
///   initialization.
abstract contract ERC_YB {
    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                           EVENTS                           */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Emitted when `amount` tokens is transferred from `from` to `to`.
    event Transfer(address indexed from, address indexed to, uint256 amount);

    /// @dev Emitted when `amount` tokens is approved by `owner` to be used by `spender`.
    event Approval(address indexed owner, address indexed spender, uint256 amount);

    /// @dev Emitted when `target` sets their skipNFT flag to `status`.
    event SkipNFTSet(address indexed target, bool status);

    /// @dev `keccak256(bytes("Transfer(address,address,uint256)"))`.
    uint256 private constant _TRANSFER_EVENT_SIGNATURE =
    0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef;

    /// @dev `keccak256(bytes("Approval(address,address,uint256)"))`.
    uint256 private constant _APPROVAL_EVENT_SIGNATURE =
    0x8c5be1e5ebec7d5bd14f71427d1e84f3dd0314c0f7b2291e5b200ac8c7c3b925;

    /// @dev `keccak256(bytes("SkipNFTSet(address,bool)"))`.
    uint256 private constant _SKIP_NFT_SET_EVENT_SIGNATURE =
    0xb5a1de456fff688115a4f75380060c23c8532d14ff85f687cc871456d6420393;

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                        CUSTOM ERRORS                       */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Thrown when attempting to double-initialize the contract.
    error DNAlreadyInitialized();

    /// @dev Thrown when attempting to transfer or burn more tokens than sender's balance.
    error InsufficientBalance();

    /// @dev Thrown when a spender attempts to transfer tokens with an insufficient allowance.
    error InsufficientAllowance();

    /// @dev Thrown when minting an amount of tokens that would overflow the max tokens.
    error TotalSupplyOverflow();

    /// @dev The unit cannot be zero.
    error UnitIsZero();

    /// @dev Thrown when the caller for a fallback NFT function is not the mirror contract.
    error SenderNotMirror();

    /// @dev Thrown when attempting to transfer tokens to the zero address.
    error TransferToZeroAddress();

    /// @dev Thrown when the mirror address provided for initialization is the zero address.
    error MirrorAddressIsZero();

    /// @dev Thrown when the link call to the mirror contract reverts.
    error LinkMirrorContractFailed();

    /// @dev Thrown when setting an NFT token approval
    /// and the caller is not the owner or an approved operator.
    error ApprovalCallerNotOwnerNorApproved();

    /// @dev Thrown when transferring an NFT
    /// and the caller is not the owner or an approved operator.
    error TransferCallerNotOwnerNorApproved();

    /// @dev Thrown when transferring an NFT and the from address is not the current owner.
    error TransferFromIncorrectOwner();

    /// @dev Thrown when checking the owner or approved address for a non-existent NFT.
    error TokenDoesNotExist();

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                         CONSTANTS                          */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev The flag to denote that the address data is initialized.
    uint8 internal constant _ADDRESS_DATA_INITIALIZED_FLAG = 1 << 0;

    /// @dev The flag to denote that the address should skip NFTs.
    uint8 internal constant _ADDRESS_DATA_SKIP_NFT_FLAG = 1 << 1;

    /// @dev The flag to denote that the address has overridden the default Permit2 allowance.
    uint8 internal constant _ADDRESS_DATA_OVERRIDE_PERMIT2_FLAG = 1 << 2;

    /// @dev The canonical Permit2 address.
    /// For signature-based allowance granting for single transaction ERC20 `transferFrom`.
    /// To enable, override `_givePermit2DefaultInfiniteAllowance()`.
    /// [Github](https://github.com/Uniswap/permit2)
    /// [Etherscan](https://etherscan.io/address/0x000000000022D473030F116dDEE9F6B43aC78BA3)
    address internal constant _PERMIT2 = 0x000000000022D473030F116dDEE9F6B43aC78BA3;

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                          STORAGE                           */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Struct containing an address's token data and settings.
    struct AddressData {
        // Auxiliary data.
        uint88 aux;
        // Flags for `initialized` and `skipNFT`.
        uint8 flags;
        // The alias for the address. Zero means absence of an alias.
        uint32 addressAlias;
        // The number of NFT tokens.
        uint32 ownedLength;
        // The token balance in wei.
        uint96 balance;
    }

    /// @dev A uint32 map in storage.
    struct Uint32Map {
        uint256 spacer;
    }

    /// @dev A bitmap in storage.
    struct Bitmap {
        uint256 spacer;
    }

    /// @dev A struct to wrap a uint256 in storage.
    struct Uint256Ref {
        uint256 value;
    }

    /// @dev A mapping of an address pair to a Uint256Ref.
    struct AddressPairToUint256RefMap {
        uint256 spacer;
    }

    /// @dev Struct containing the base token contract storage.
    struct DN404Storage {
        // Current number of address aliases assigned.
        uint32 numAliases;
        // Next token ID to assign for an NFT mint.
        uint32 nextTokenId;
        // Total number of IDs in the burned pool.
        uint32 burnedPoolSize;
        // Total supply of minted NFTs.
        uint32 totalNFTSupply;
        // Total supply of tokens.
        uint96 totalSupply;
        // Address of the NFT mirror contract.
        address mirrorERC721;
        // Mapping of a user alias number to their address.
        mapping(uint32 => address) aliasToAddress;
        // Mapping of user operator approvals for NFTs.
        AddressPairToUint256RefMap operatorApprovals;
        // Mapping of NFT token approvals to approved operators.
        mapping(uint256 => address) nftApprovals;
        // Bitmap of whether an non-zero NFT approval may exist.
        Bitmap mayHaveNFTApproval;
        // Mapping of user allowances for token spenders.
        AddressPairToUint256RefMap allowance;
        // Mapping of NFT IDs owned by an address.
        mapping(address => Uint32Map) owned;
        // The pool of burned NFT IDs.
        Uint32Map burnedPool;
        // Even indices: owner aliases. Odd indices: owned indices.
        Uint32Map oo;
        // Mapping of user account AddressData.
        mapping(address => AddressData) addressData;
    }

    /// @dev Returns a storage pointer for DN404Storage.
    function _getDN404Storage() internal pure virtual returns (DN404Storage storage $) {
        /// @solidity memory-safe-assembly
        assembly {
        // `uint72(bytes9(keccak256("DN404_STORAGE")))`.
            $.slot := 0xa20d6e21d0e5255308 // Truncate to 9 bytes to reduce bytecode size.
        }
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                         INITIALIZER                        */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Initializes the DN404 contract with an
    /// `initialTokenSupply`, `initialTokenOwner` and `mirror` NFT contract address.
    function _initializeDN404(
        uint256 initialTokenSupply,
        address initialSupplyOwner,
        address mirror
    ) internal virtual {
        DN404Storage storage $ = _getDN404Storage();

        if ($.nextTokenId != 0) revert DNAlreadyInitialized();

        if (mirror == address(0)) revert MirrorAddressIsZero();

        /// @solidity memory-safe-assembly
        assembly {
        // Make the call to link the mirror contract.
            mstore(0x00, 0x0f4599e5) // `linkMirrorContract(address)`.
            mstore(0x20, caller())
            if iszero(and(eq(mload(0x00), 1), call(gas(), mirror, 0, 0x1c, 0x24, 0x00, 0x20))) {
                mstore(0x00, 0xd125259c) // `LinkMirrorContractFailed()`.
                revert(0x1c, 0x04)
            }
        }

        $.nextTokenId = 1;
        $.mirrorERC721 = mirror;

        if (_unit() == 0) revert UnitIsZero();

        if (initialTokenSupply != 0) {
            if (initialSupplyOwner == address(0)) revert TransferToZeroAddress();
            if (_totalSupplyOverflows(initialTokenSupply)) revert TotalSupplyOverflow();

            $.totalSupply = uint96(initialTokenSupply);
            AddressData storage initialOwnerAddressData = _addressData(initialSupplyOwner);
            initialOwnerAddressData.balance = uint96(initialTokenSupply);

            /// @solidity memory-safe-assembly
            assembly {
            // Emit the {Transfer} event.
                mstore(0x00, initialTokenSupply)
                log3(0x00, 0x20, _TRANSFER_EVENT_SIGNATURE, 0, shr(96, shl(96, initialSupplyOwner)))
            }

            _setSkipNFT(initialSupplyOwner, true);
        }
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*               BASE UNIT FUNCTION TO OVERRIDE               */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Amount of token balance that is equal to one NFT.
    function _unit() internal view virtual returns (uint256) {
        return 10 ** 18;
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*               METADATA FUNCTIONS TO OVERRIDE               */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Returns the name of the token.
    function name() public view virtual returns (string memory);

    /// @dev Returns the symbol of the token.
    function symbol() public view virtual returns (string memory);

    /// @dev Returns the Uniform Resource Identifier (URI) for token `id`.
    function tokenURI(uint256 id) public view virtual returns (string memory);

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                      ERC20 OPERATIONS                      */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Returns the decimals places of the token. Always 18.
    function decimals() public pure returns (uint8) {
        return 18;
    }

    /// @dev Returns the amount of tokens in existence.
    function totalSupply() public view virtual returns (uint256) {
        return uint256(_getDN404Storage().totalSupply);
    }

    /// @dev Returns the amount of tokens owned by `owner`.
    function balanceOf(address owner) public view virtual returns (uint256) {
        return _getDN404Storage().addressData[owner].balance;
    }

    /// @dev Returns the amount of tokens that `spender` can spend on behalf of `owner`.
    function allowance(address owner, address spender) public view returns (uint256) {
        if (_givePermit2DefaultInfiniteAllowance() && spender == _PERMIT2) {
            uint8 flags = _getDN404Storage().addressData[owner].flags;
            if (flags & _ADDRESS_DATA_OVERRIDE_PERMIT2_FLAG == 0) return type(uint256).max;
        }
        return _ref(_getDN404Storage().allowance, owner, spender).value;
    }

    /// @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
    ///
    /// Emits a {Approval} event.
    function approve(address spender, uint256 amount) public virtual returns (bool) {
        _approve(msg.sender, spender, amount);
        return true;
    }

    /// @dev Transfer `amount` tokens from the caller to `to`.
    ///
    /// Will burn sender NFTs if balance after transfer is less than
    /// the amount required to support the current NFT balance.
    ///
    /// Will mint NFTs to `to` if the recipient's new balance supports
    /// additional NFTs ***AND*** the `to` address's skipNFT flag is
    /// set to false.
    ///
    /// Requirements:
    /// - `from` must at least have `amount`.
    ///
    /// Emits a {Transfer} event.
    function transfer(address to, uint256 amount) public virtual returns (bool) {
        _transfer(msg.sender, to, amount);
        return true;
    }

    /// @dev Transfers `amount` tokens from `from` to `to`.
    ///
    /// Note: Does not update the allowance if it is the maximum uint256 value.
    ///
    /// Will burn sender NFTs if balance after transfer is less than
    /// the amount required to support the current NFT balance.
    ///
    /// Will mint NFTs to `to` if the recipient's new balance supports
    /// additional NFTs ***AND*** the `to` address's skipNFT flag is
    /// set to false.
    ///
    /// Requirements:
    /// - `from` must at least have `amount`.
    /// - The caller must have at least `amount` of allowance to transfer the tokens of `from`.
    ///
    /// Emits a {Transfer} event.
    function transferFrom(address from, address to, uint256 amount) public virtual returns (bool) {
        Uint256Ref storage a = _ref(_getDN404Storage().allowance, from, msg.sender);

        uint256 allowed = _givePermit2DefaultInfiniteAllowance() && msg.sender == _PERMIT2
        && (_getDN404Storage().addressData[from].flags & _ADDRESS_DATA_OVERRIDE_PERMIT2_FLAG) == 0
            ? type(uint256).max
            : a.value;

        if (allowed != type(uint256).max) {
            if (amount > allowed) revert InsufficientAllowance();
            unchecked {
                a.value = allowed - amount;
            }
        }
        _transfer(from, to, amount);
        return true;
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                          PERMIT2                           */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Whether Permit2 has infinite allowances by default for all owners.
    /// For signature-based allowance granting for single transaction ERC20 `transferFrom`.
    /// To enable, override this function to return true.
    function _givePermit2DefaultInfiniteAllowance() internal view virtual returns (bool) {
        return false;
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                  INTERNAL MINT FUNCTIONS                   */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Mints `amount` tokens to `to`, increasing the total supply.
    ///
    /// Will mint NFTs to `to` if the recipient's new balance supports
    /// additional NFTs ***AND*** the `to` address's skipNFT flag is
    /// set to false.
    ///
    /// Emits a {Transfer} event.
    function _mint(address to, uint256 amount) internal virtual {
        if (to == address(0)) revert TransferToZeroAddress();

        DN404Storage storage $ = _getDN404Storage();

        AddressData storage toAddressData = _addressData(to);

        unchecked {
            uint256 maxNFTId;
            {
                uint256 totalSupply_ = uint256($.totalSupply) + amount;
                $.totalSupply = uint96(totalSupply_);
                uint256 overflows = _toUint(_totalSupplyOverflows(totalSupply_));
                if (overflows | _toUint(totalSupply_ < amount) != 0) revert TotalSupplyOverflow();
                maxNFTId = totalSupply_ / _unit();
            }
            uint256 toEnd;
            {
                uint256 toBalance = uint256(toAddressData.balance) + amount;
                toAddressData.balance = uint96(toBalance);
                toEnd = toBalance / _unit();
            }
            if (toAddressData.flags & _ADDRESS_DATA_SKIP_NFT_FLAG == 0) {
                Uint32Map storage toOwned = $.owned[to];
                Uint32Map storage oo = $.oo;
                uint256 toIndex = toAddressData.ownedLength;
                _PackedLogs memory packedLogs = _packedLogsMalloc(_zeroFloorSub(toEnd, toIndex));

                if (packedLogs.logs.length != 0) {
                    _packedLogsSet(packedLogs, to, 0);
                    uint256 burnedPoolSize = $.burnedPoolSize;
                    uint256 nextTokenId = $.nextTokenId;
                    uint32 toAlias = _registerAndResolveAlias(toAddressData, to);
                    $.totalNFTSupply += uint32(packedLogs.logs.length);
                    toAddressData.ownedLength = uint32(toEnd);
                    // Mint loop.
                    do {
                        uint256 id;
                        if (burnedPoolSize != 0) {
                            id = _get($.burnedPool, --burnedPoolSize);
                        } else {
                            id = nextTokenId;
                            while (_get(oo, _ownershipIndex(id)) != 0) {
                                id = _wrapNFTId(id + 1, maxNFTId);
                            }
                            nextTokenId = _wrapNFTId(id + 1, maxNFTId);
                        }
                        _set(toOwned, toIndex, uint32(id));
                        _setOwnerAliasAndOwnedIndex(oo, id, toAlias, uint32(toIndex++));
                        _packedLogsAppend(packedLogs, id);
                    } while (toIndex != toEnd);

                    // Leave some spacing between minted batches for better open addressing.
                    $.nextTokenId = uint32(_wrapNFTId(nextTokenId + 7, maxNFTId));
                    $.burnedPoolSize = uint32(burnedPoolSize);
                    _packedLogsSend(packedLogs, $.mirrorERC721);
                }
            }
        }
        /// @solidity memory-safe-assembly
        assembly {
        // Emit the {Transfer} event.
            mstore(0x00, amount)
            log3(0x00, 0x20, _TRANSFER_EVENT_SIGNATURE, 0, shr(96, shl(96, to)))
        }
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                  INTERNAL BURN FUNCTIONS                   */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Burns `amount` tokens from `from`, reducing the total supply.
    ///
    /// Will burn sender NFTs if balance after transfer is less than
    /// the amount required to support the current NFT balance.
    ///
    /// Emits a {Transfer} event.
    function _burn(address from, uint256 amount) internal virtual {
        DN404Storage storage $ = _getDN404Storage();

        AddressData storage fromAddressData = _addressData(from);

        uint256 fromBalance = fromAddressData.balance;
        if (amount > fromBalance) revert InsufficientBalance();

        unchecked {
            fromAddressData.balance = uint96(fromBalance -= amount);
            uint256 totalSupply_ = uint256($.totalSupply) - amount;
            $.totalSupply = uint96(totalSupply_);

            Uint32Map storage fromOwned = $.owned[from];
            uint256 fromIndex = fromAddressData.ownedLength;
            uint256 numNFTBurns = _zeroFloorSub(fromIndex, fromBalance / _unit());

            if (numNFTBurns != 0) {
                _PackedLogs memory packedLogs = _packedLogsMalloc(numNFTBurns);
                _packedLogsSet(packedLogs, from, 1);
                uint256 totalNFTSupply = uint256($.totalNFTSupply) - numNFTBurns;
                $.totalNFTSupply = uint32(totalNFTSupply);
                bool addToBurnedPool = _addToBurnedPool(totalNFTSupply, totalSupply_);

                Uint32Map storage oo = $.oo;
                uint256 fromEnd = fromIndex - numNFTBurns;
                fromAddressData.ownedLength = uint32(fromEnd);
                uint256 burnedPoolSize = $.burnedPoolSize;
                // Burn loop.
                do {
                    uint256 id = _get(fromOwned, --fromIndex);
                    _setOwnerAliasAndOwnedIndex(oo, id, 0, 0);
                    _packedLogsAppend(packedLogs, id);
                    if (addToBurnedPool) {
                        _set($.burnedPool, burnedPoolSize++, uint32(id));
                    }
                    if (_get($.mayHaveNFTApproval, id)) {
                        _set($.mayHaveNFTApproval, id, false);
                        delete $.nftApprovals[id];
                    }
                } while (fromIndex != fromEnd);

                $.burnedPoolSize = uint32(burnedPoolSize);
                _packedLogsSend(packedLogs, $.mirrorERC721);
            }
        }
        /// @solidity memory-safe-assembly
        assembly {
        // Emit the {Transfer} event.
            mstore(0x00, amount)
            log3(0x00, 0x20, _TRANSFER_EVENT_SIGNATURE, shr(96, shl(96, from)), 0)
        }
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                INTERNAL TRANSFER FUNCTIONS                 */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Moves `amount` of tokens from `from` to `to`.
    ///
    /// Will burn sender NFTs if balance after transfer is less than
    /// the amount required to support the current NFT balance.
    ///
    /// Will mint NFTs to `to` if the recipient's new balance supports
    /// additional NFTs ***AND*** the `to` address's skipNFT flag is
    /// set to false.
    ///
    /// Emits a {Transfer} event.
    function _transfer(address from, address to, uint256 amount) internal virtual {
        if (to == address(0)) revert TransferToZeroAddress();

        DN404Storage storage $ = _getDN404Storage();

        AddressData storage fromAddressData = _addressData(from);
        AddressData storage toAddressData = _addressData(to);

        _TransferTemps memory t;
        t.fromOwnedLength = fromAddressData.ownedLength;
        t.toOwnedLength = toAddressData.ownedLength;
        t.totalSupply = $.totalSupply;

        if (amount > (t.fromBalance = fromAddressData.balance)) revert InsufficientBalance();

        unchecked {
            fromAddressData.balance = uint96(t.fromBalance -= amount);
            toAddressData.balance = uint96(t.toBalance = uint256(toAddressData.balance) + amount);

            t.numNFTBurns = _zeroFloorSub(t.fromOwnedLength, t.fromBalance / _unit());

            if (toAddressData.flags & _ADDRESS_DATA_SKIP_NFT_FLAG == 0) {
                if (from == to) t.toOwnedLength = t.fromOwnedLength - t.numNFTBurns;
                t.numNFTMints = _zeroFloorSub(t.toBalance / _unit(), t.toOwnedLength);
            }

            t.totalNFTSupply = uint256($.totalNFTSupply) + t.numNFTMints - t.numNFTBurns;
            $.totalNFTSupply = uint32(t.totalNFTSupply);

            _PackedLogs memory packedLogs = _packedLogsMalloc(t.numNFTBurns + t.numNFTMints);
            Uint32Map storage oo = $.oo;

            uint256 burnedPoolSize = $.burnedPoolSize;
            if (t.numNFTBurns != 0) {
                _packedLogsSet(packedLogs, from, 1);
                bool addToBurnedPool = _addToBurnedPool(t.totalNFTSupply, t.totalSupply);
                Uint32Map storage fromOwned = $.owned[from];
                uint256 fromIndex = t.fromOwnedLength;
                uint256 fromEnd = fromIndex - t.numNFTBurns;
                fromAddressData.ownedLength = uint32(fromEnd);
                // Burn loop.
                do {
                    uint256 id = _get(fromOwned, --fromIndex);
                    _setOwnerAliasAndOwnedIndex(oo, id, 0, 0);
                    _packedLogsAppend(packedLogs, id);
                    if (addToBurnedPool) {
                        _set($.burnedPool, burnedPoolSize++, uint32(id));
                    }
                    if (_get($.mayHaveNFTApproval, id)) {
                        _set($.mayHaveNFTApproval, id, false);
                        delete $.nftApprovals[id];
                    }
                } while (fromIndex != fromEnd);
            }

            if (t.numNFTMints != 0) {
                _packedLogsSet(packedLogs, to, 0);
                uint256 nextTokenId = $.nextTokenId;
                Uint32Map storage toOwned = $.owned[to];
                uint256 toIndex = t.toOwnedLength;
                uint256 toEnd = toIndex + t.numNFTMints;
                uint32 toAlias = _registerAndResolveAlias(toAddressData, to);
                uint256 maxNFTId = t.totalSupply / _unit();
                toAddressData.ownedLength = uint32(toEnd);
                // Mint loop.
                do {
                    uint256 id;
                    if (burnedPoolSize != 0) {
                        id = _get($.burnedPool, --burnedPoolSize);
                    } else {
                        id = nextTokenId;
                        while (_get(oo, _ownershipIndex(id)) != 0) {
                            id = _wrapNFTId(id + 1, maxNFTId);
                        }
                        nextTokenId = _wrapNFTId(id + 1, maxNFTId);
                    }
                    _set(toOwned, toIndex, uint32(id));
                    _setOwnerAliasAndOwnedIndex(oo, id, toAlias, uint32(toIndex++));
                    _packedLogsAppend(packedLogs, id);
                } while (toIndex != toEnd);

                // Leave some spacing between minted batches for better open addressing.
                $.nextTokenId = uint32(_wrapNFTId(nextTokenId + 7, maxNFTId));
            }

            if (packedLogs.logs.length != 0) {
                $.burnedPoolSize = uint32(burnedPoolSize);
                _packedLogsSend(packedLogs, $.mirrorERC721);
            }
        }
        /// @solidity memory-safe-assembly
        assembly {
        // Emit the {Transfer} event.
            mstore(0x00, amount)
        // forgefmt: disable-next-item
            log3(0x00, 0x20, _TRANSFER_EVENT_SIGNATURE, shr(96, shl(96, from)), shr(96, shl(96, to)))
        }
    }

    /// @dev Returns if burns should be added to the burn pool.
    function _addToBurnedPool(uint256 totalNFTSupplyAfterBurn, uint256 totalSupplyAfterBurn)
    internal
    view
    virtual
    returns (bool)
    {
        // Add to burned pool if the load factor > 50%, and collection is not small.
        uint256 thres = (totalSupplyAfterBurn / _unit()) >> 1;
        return _toUint(totalNFTSupplyAfterBurn > thres) & _toUint(thres > 128) != 0;
    }

    /// @dev Transfers token `id` from `from` to `to`.
    ///
    /// Requirements:
    ///
    /// - Call must originate from the mirror contract.
    /// - Token `id` must exist.
    /// - `from` must be the owner of the token.
    /// - `to` cannot be the zero address.
    ///   `msgSender` must be the owner of the token, or be approved to manage the token.
    ///
    /// Emits a {Transfer} event.
    function _transferFromNFT(address from, address to, uint256 id, address msgSender)
    internal
    virtual
    {
        DN404Storage storage $ = _getDN404Storage();

        if (to == address(0)) revert TransferToZeroAddress();

        Uint32Map storage oo = $.oo;

        if (from != $.aliasToAddress[_get(oo, _ownershipIndex(id))]) {
            revert TransferFromIncorrectOwner();
        }

        if (msgSender != from) {
            if (_ref($.operatorApprovals, from, msgSender).value == 0) {
                if (msgSender != $.nftApprovals[id]) {
                    revert TransferCallerNotOwnerNorApproved();
                }
            }
        }

        AddressData storage fromAddressData = _addressData(from);
        AddressData storage toAddressData = _addressData(to);

        uint256 unit = _unit();

        unchecked {
            {
                uint256 fromBalance = fromAddressData.balance;
                if (unit > fromBalance) revert InsufficientBalance();
                fromAddressData.balance = uint96(fromBalance - unit);
                toAddressData.balance += uint96(unit);
            }
            mapping(address => Uint32Map) storage owned = $.owned;
            Uint32Map storage fromOwned = owned[from];

            if (_get($.mayHaveNFTApproval, id)) {
                _set($.mayHaveNFTApproval, id, false);
                delete $.nftApprovals[id];
            }

            {
                uint32 updatedId = _get(fromOwned, --fromAddressData.ownedLength);
                uint32 i = _get(oo, _ownedIndex(id));
                _set(fromOwned, i, updatedId);
                _set(oo, _ownedIndex(updatedId), i);
            }
            uint32 n = toAddressData.ownedLength++;
            _set(owned[to], n, uint32(id));
            _setOwnerAliasAndOwnedIndex(oo, id, _registerAndResolveAlias(toAddressData, to), n);
        }

        /// @solidity memory-safe-assembly
        assembly {
        // Emit the {Transfer} event.
            mstore(0x00, unit)
        // forgefmt: disable-next-item
            log3(0x00, 0x20, _TRANSFER_EVENT_SIGNATURE, shr(96, shl(96, from)), shr(96, shl(96, to)))
        }
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                 INTERNAL APPROVE FUNCTIONS                 */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Sets `amount` as the allowance of `spender` over the tokens of `owner`.
    ///
    /// Emits a {Approval} event.
    function _approve(address owner, address spender, uint256 amount) internal virtual {
        if (_givePermit2DefaultInfiniteAllowance() && spender == _PERMIT2) {
            _getDN404Storage().addressData[owner].flags |= _ADDRESS_DATA_OVERRIDE_PERMIT2_FLAG;
        }
        _ref(_getDN404Storage().allowance, owner, spender).value = amount;
        /// @solidity memory-safe-assembly
        assembly {
        // Emit the {Approval} event.
            mstore(0x00, amount)
        // forgefmt: disable-next-item
            log3(0x00, 0x20, _APPROVAL_EVENT_SIGNATURE, shr(96, shl(96, owner)), shr(96, shl(96, spender)))
        }
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                 DATA HITCHHIKING FUNCTIONS                 */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Returns the auxiliary data for `owner`.
    /// Minting, transferring, burning the tokens of `owner` will not change the auxiliary data.
    /// Auxiliary data can be set for any address, even if it does not have any tokens.
    function _getAux(address owner) internal view virtual returns (uint88) {
        return _getDN404Storage().addressData[owner].aux;
    }

    /// @dev Set the auxiliary data for `owner` to `value`.
    /// Minting, transferring, burning the tokens of `owner` will not change the auxiliary data.
    /// Auxiliary data can be set for any address, even if it does not have any tokens.
    function _setAux(address owner, uint88 value) internal virtual {
        _getDN404Storage().addressData[owner].aux = value;
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                     SKIP NFT FUNCTIONS                     */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Returns true if minting and transferring ERC20s to `owner` will skip minting NFTs.
    /// Returns false otherwise.
    function getSkipNFT(address owner) public view virtual returns (bool) {
        AddressData storage d = _getDN404Storage().addressData[owner];
        if (d.flags & _ADDRESS_DATA_INITIALIZED_FLAG == 0) return _hasCode(owner);
        return d.flags & _ADDRESS_DATA_SKIP_NFT_FLAG != 0;
    }

    /// @dev Sets the caller's skipNFT flag to `skipNFT`. Returns true.
    ///
    /// Emits a {SkipNFTSet} event.
    function setSkipNFT(bool skipNFT) public virtual returns (bool) {
        _setSkipNFT(msg.sender, skipNFT);
        return true;
    }

    /// @dev Internal function to set account `owner` skipNFT flag to `state`
    ///
    /// Initializes account `owner` AddressData if it is not currently initialized.
    ///
    /// Emits a {SkipNFTSet} event.
    function _setSkipNFT(address owner, bool state) internal virtual {
        AddressData storage d = _addressData(owner);
        if ((d.flags & _ADDRESS_DATA_SKIP_NFT_FLAG != 0) != state) {
            d.flags ^= _ADDRESS_DATA_SKIP_NFT_FLAG;
        }
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x00, iszero(iszero(state)))
            log2(0x00, 0x20, _SKIP_NFT_SET_EVENT_SIGNATURE, shr(96, shl(96, owner)))
        }
    }

    /// @dev Returns a storage data pointer for account `owner` AddressData
    ///
    /// Initializes account `owner` AddressData if it is not currently initialized.
    function _addressData(address owner) internal virtual returns (AddressData storage d) {
        d = _getDN404Storage().addressData[owner];
        unchecked {
            if (d.flags & _ADDRESS_DATA_INITIALIZED_FLAG == 0) {
                uint256 skipNFT = (_toUint(_hasCode(owner)) * _ADDRESS_DATA_SKIP_NFT_FLAG);
                d.flags = uint8(skipNFT | _ADDRESS_DATA_INITIALIZED_FLAG);
            }
        }
    }

    /// @dev Returns the `addressAlias` of account `to`.
    ///
    /// Assigns and registers the next alias if `to` alias was not previously registered.
    function _registerAndResolveAlias(AddressData storage toAddressData, address to)
    internal
    virtual
    returns (uint32 addressAlias)
    {
        DN404Storage storage $ = _getDN404Storage();
        addressAlias = toAddressData.addressAlias;
        if (addressAlias == 0) {
            unchecked {
                addressAlias = ++$.numAliases;
            }
            toAddressData.addressAlias = addressAlias;
            $.aliasToAddress[addressAlias] = to;
            if (addressAlias == 0) revert(); // Overflow.
        }
    }

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                     MIRROR OPERATIONS                      */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Returns the address of the mirror NFT contract.
    function mirrorERC721() public view virtual returns (address) {
        return _getDN404Storage().mirrorERC721;
    }

    /// @dev Returns the total NFT supply.
    function _totalNFTSupply() internal view virtual returns (uint256) {
        return _getDN404Storage().totalNFTSupply;
    }

    /// @dev Returns `owner` NFT balance.
    function _balanceOfNFT(address owner) internal view virtual returns (uint256) {
        return _getDN404Storage().addressData[owner].ownedLength;
    }

    /// @dev Returns the owner of token `id`.
    /// Returns the zero address instead of reverting if the token does not exist.
    function _ownerAt(uint256 id) internal view virtual returns (address) {
        DN404Storage storage $ = _getDN404Storage();
        return $.aliasToAddress[_get($.oo, _ownershipIndex(id))];
    }

    /// @dev Returns the owner of token `id`.
    ///
    /// Requirements:
    /// - Token `id` must exist.
    function _ownerOf(uint256 id) internal view virtual returns (address) {
        if (!_exists(id)) revert TokenDoesNotExist();
        return _ownerAt(id);
    }

    /// @dev Returns if token `id` exists.
    function _exists(uint256 id) internal view virtual returns (bool) {
        return _ownerAt(id) != address(0);
    }

    /// @dev Returns the account approved to manage token `id`.
    ///
    /// Requirements:
    /// - Token `id` must exist.
    function _getApproved(uint256 id) internal view virtual returns (address) {
        if (!_exists(id)) revert TokenDoesNotExist();
        return _getDN404Storage().nftApprovals[id];
    }

    /// @dev Sets `spender` as the approved account to manage token `id`, using `msgSender`.
    ///
    /// Requirements:
    /// - `msgSender` must be the owner or an approved operator for the token owner.
    function _approveNFT(address spender, uint256 id, address msgSender)
    internal
    virtual
    returns (address owner)
    {
        DN404Storage storage $ = _getDN404Storage();

        owner = $.aliasToAddress[_get($.oo, _ownershipIndex(id))];

        if (msgSender != owner) {
            if (_ref($.operatorApprovals, owner, msgSender).value == 0) {
                revert ApprovalCallerNotOwnerNorApproved();
            }
        }

        $.nftApprovals[id] = spender;
        _set($.mayHaveNFTApproval, id, spender != address(0));
    }

    /// @dev Approve or remove the `operator` as an operator for `msgSender`,
    /// without authorization checks.
    function _setApprovalForAll(address operator, bool approved, address msgSender)
    internal
    virtual
    {
        _ref(_getDN404Storage().operatorApprovals, msgSender, operator).value = _toUint(approved);
    }

    /// @dev Fallback modifier to dispatch calls from the mirror NFT contract
    /// to internal functions in this contract.
    modifier dn404Fallback() virtual {
        DN404Storage storage $ = _getDN404Storage();

        uint256 fnSelector = _calldataload(0x00) >> 224;

        // `transferFromNFT(address,address,uint256,address)`.
        if (fnSelector == 0xe5eb36c8) {
            if (msg.sender != $.mirrorERC721) revert SenderNotMirror();
            if (msg.data.length < 0x84) revert();

            address from = address(uint160(_calldataload(0x04)));
            address to = address(uint160(_calldataload(0x24)));
            uint256 id = _calldataload(0x44);
            address msgSender = address(uint160(_calldataload(0x64)));

            _transferFromNFT(from, to, id, msgSender);
            _return(1);
        }
        // `setApprovalForAll(address,bool,address)`.
        if (fnSelector == 0x813500fc) {
            if (msg.sender != $.mirrorERC721) revert SenderNotMirror();
            if (msg.data.length < 0x64) revert();

            address spender = address(uint160(_calldataload(0x04)));
            bool status = _calldataload(0x24) != 0;
            address msgSender = address(uint160(_calldataload(0x44)));

            _setApprovalForAll(spender, status, msgSender);
            _return(1);
        }
        // `isApprovedForAll(address,address)`.
        if (fnSelector == 0xe985e9c5) {
            if (msg.sender != $.mirrorERC721) revert SenderNotMirror();
            if (msg.data.length < 0x44) revert();

            address owner = address(uint160(_calldataload(0x04)));
            address operator = address(uint160(_calldataload(0x24)));

            _return(_ref($.operatorApprovals, owner, operator).value);
        }
        // `ownerOf(uint256)`.
        if (fnSelector == 0x6352211e) {
            if (msg.sender != $.mirrorERC721) revert SenderNotMirror();
            if (msg.data.length < 0x24) revert();

            uint256 id = _calldataload(0x04);

            _return(uint160(_ownerOf(id)));
        }
        // `ownerAt(uint256)`.
        if (fnSelector == 0x24359879) {
            if (msg.sender != $.mirrorERC721) revert SenderNotMirror();
            if (msg.data.length < 0x24) revert();

            uint256 id = _calldataload(0x04);

            _return(uint160(_ownerAt(id)));
        }
        // `approveNFT(address,uint256,address)`.
        if (fnSelector == 0xd10b6e0c) {
            if (msg.sender != $.mirrorERC721) revert SenderNotMirror();
            if (msg.data.length < 0x64) revert();

            address spender = address(uint160(_calldataload(0x04)));
            uint256 id = _calldataload(0x24);
            address msgSender = address(uint160(_calldataload(0x44)));

            _return(uint160(_approveNFT(spender, id, msgSender)));
        }
        // `getApproved(uint256)`.
        if (fnSelector == 0x081812fc) {
            if (msg.sender != $.mirrorERC721) revert SenderNotMirror();
            if (msg.data.length < 0x24) revert();

            uint256 id = _calldataload(0x04);

            _return(uint160(_getApproved(id)));
        }
        // `balanceOfNFT(address)`.
        if (fnSelector == 0xf5b100ea) {
            if (msg.sender != $.mirrorERC721) revert SenderNotMirror();
            if (msg.data.length < 0x24) revert();

            address owner = address(uint160(_calldataload(0x04)));

            _return(_balanceOfNFT(owner));
        }
        // `totalNFTSupply()`.
        if (fnSelector == 0xe2c79281) {
            if (msg.sender != $.mirrorERC721) revert SenderNotMirror();
            if (msg.data.length < 0x04) revert();

            _return(_totalNFTSupply());
        }
        // `implementsDN404()`.
        if (fnSelector == 0xb7a94eb8) {
            _return(1);
        }
        _;
    }

    /// @dev Fallback function for calls from mirror NFT contract.
    fallback() external payable virtual dn404Fallback {}

    receive() external payable virtual {}

    /*«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-«-*/
    /*                 INTERNAL / PRIVATE HELPERS                 */
    /*-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»-»*/

    /// @dev Returns `(i - 1) << 1`.
    function _ownershipIndex(uint256 i) internal pure returns (uint256) {
        unchecked {
            return (i - 1) << 1; // Minus 1 as token IDs start from 1.
        }
    }

    /// @dev Returns `((i - 1) << 1) + 1`.
    function _ownedIndex(uint256 i) internal pure returns (uint256) {
        unchecked {
            return ((i - 1) << 1) + 1; // Minus 1 as token IDs start from 1.
        }
    }

    /// @dev Returns the uint32 value at `index` in `map`.
    function _get(Uint32Map storage map, uint256 index) internal view returns (uint32 result) {
        /// @solidity memory-safe-assembly
        assembly {
            let s := add(shl(96, map.slot), shr(3, index)) // Storage slot.
            result := and(0xffffffff, shr(shl(5, and(index, 7)), sload(s)))
        }
    }

    /// @dev Updates the uint32 value at `index` in `map`.
    function _set(Uint32Map storage map, uint256 index, uint32 value) internal {
        /// @solidity memory-safe-assembly
        assembly {
            let s := add(shl(96, map.slot), shr(3, index)) // Storage slot.
            let o := shl(5, and(index, 7)) // Storage slot offset (bits).
            let v := sload(s) // Storage slot value.
            let m := 0xffffffff // Value mask.
            sstore(s, xor(v, shl(o, and(m, xor(shr(o, v), value)))))
        }
    }

    /// @dev Sets the owner alias and the owned index together.
    function _setOwnerAliasAndOwnedIndex(
        Uint32Map storage map,
        uint256 id,
        uint32 ownership,
        uint32 ownedIndex
    ) internal {
        /// @solidity memory-safe-assembly
        assembly {
            let i := sub(id, 1) // Index of the uint64 combined value.
            let s := add(shl(96, map.slot), shr(2, i)) // Storage slot.
            let o := shl(6, and(i, 3)) // Storage slot offset (bits).
            let v := sload(s) // Storage slot value.
            let m := 0xffffffffffffffff // Value mask.
            let combined := or(shl(32, ownedIndex), and(0xffffffff, ownership))
            sstore(s, xor(v, shl(o, and(m, xor(shr(o, v), combined)))))
        }
    }

    /// @dev Returns the boolean value of the bit at `index` in `bitmap`.
    function _get(Bitmap storage bitmap, uint256 index) internal view returns (bool result) {
        /// @solidity memory-safe-assembly
        assembly {
            let s := add(shl(96, bitmap.slot), shr(8, index)) // Storage slot.
            result := and(1, shr(and(0xff, index), sload(s)))
        }
    }

    /// @dev Updates the bit at `index` in `bitmap` to `value`.
    function _set(Bitmap storage bitmap, uint256 index, bool value) internal {
        /// @solidity memory-safe-assembly
        assembly {
            let s := add(shl(96, bitmap.slot), shr(8, index)) // Storage slot.
            let o := and(0xff, index) // Storage slot offset (bits).
            sstore(s, or(and(sload(s), not(shl(o, 1))), shl(o, iszero(iszero(value)))))
        }
    }

    /// @dev Returns a storage reference to the value at (`a0`, `a1`) in `map`.
    function _ref(AddressPairToUint256RefMap storage map, address a0, address a1)
    internal
    pure
    returns (Uint256Ref storage ref)
    {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x28, a1)
            mstore(0x14, a0)
            mstore(0x00, map.slot)
            ref.slot := keccak256(0x00, 0x48)
        // Clear the part of the free memory pointer that was overwritten.
            mstore(0x28, 0x00)
        }
    }

    /// @dev Wraps the NFT ID.
    function _wrapNFTId(uint256 id, uint256 maxNFTId) internal pure returns (uint256 result) {
        /// @solidity memory-safe-assembly
        assembly {
            result := or(mul(iszero(gt(id, maxNFTId)), id), gt(id, maxNFTId))
        }
    }

    /// @dev Returns whether `amount` is a valid `totalSupply`.
    function _totalSupplyOverflows(uint256 amount) internal view returns (bool) {
        unchecked {
            return _toUint(amount > type(uint96).max)
            | _toUint(amount / _unit() > type(uint32).max - 1) != 0;
        }
    }

    /// @dev Returns `max(0, x - y)`.
    function _zeroFloorSub(uint256 x, uint256 y) internal pure returns (uint256 z) {
        /// @solidity memory-safe-assembly
        assembly {
            z := mul(gt(x, y), sub(x, y))
        }
    }

    /// @dev Returns `b ? 1 : 0`.
    function _toUint(bool b) internal pure returns (uint256 result) {
        /// @solidity memory-safe-assembly
        assembly {
            result := iszero(iszero(b))
        }
    }

    /// @dev Struct containing packed log data for {Transfer} events to be
    /// emitted by the mirror NFT contract.
    struct _PackedLogs {
        uint256 offset;
        uint256 addressAndBit;
        uint256[] logs;
    }

    /// @dev Initiates memory allocation for packed logs with `n` log items.
    function _packedLogsMalloc(uint256 n) private pure returns (_PackedLogs memory p) {
        /// @solidity memory-safe-assembly
        assembly {
        // Note that `p` implicitly allocates and advances the free memory pointer by
        // 3 words, which we can safely mutate in `_packedLogsSend`.
            let logs := mload(0x40)
            mstore(logs, n) // Store the length.
            let offset := add(0x20, logs) // Skip the word for `p.logs.length`.
            mstore(0x40, add(offset, shl(5, n))) // Allocate memory.
            mstore(add(0x40, p), logs) // Set `p.logs`.
            mstore(p, offset) // Set `p.offset`.
        }
    }

    /// @dev Set the current address and the burn bit.
    function _packedLogsSet(_PackedLogs memory p, address a, uint256 burnBit) private pure {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(add(p, 0x20), or(shl(96, a), burnBit)) // Set `p.addressAndBit`.
        }
    }

    /// @dev Adds a packed log item to `p` with token `id`.
    function _packedLogsAppend(_PackedLogs memory p, uint256 id) private pure {
        /// @solidity memory-safe-assembly
        assembly {
            let offset := mload(p)
            mstore(offset, or(mload(add(p, 0x20)), shl(8, id))) // `p.addressAndBit | (id << 8)`.
            mstore(p, add(offset, 0x20))
        }
    }

    /// @dev Calls the `mirror` NFT contract to emit {Transfer} events for packed logs `p`.
    function _packedLogsSend(_PackedLogs memory p, address mirror) private {
        /// @solidity memory-safe-assembly
        assembly {
            let logs := mload(add(p, 0x40))
            let o := sub(logs, 0x40) // Start of calldata to send.
            mstore(o, 0x263c69d6) // `logTransfer(uint256[])`.
            mstore(add(o, 0x20), 0x20) // Offset of `logs` in the calldata to send.
            let n := add(0x44, shl(5, mload(logs))) // Length of calldata to send.
            if iszero(and(eq(mload(o), 1), call(gas(), mirror, 0, add(o, 0x1c), n, o, 0x20))) {
                revert(o, 0x00)
            }
        }
    }

    /// @dev Struct of temporary variables for transfers.
    struct _TransferTemps {
        uint256 numNFTBurns;
        uint256 numNFTMints;
        uint256 fromBalance;
        uint256 toBalance;
        uint256 fromOwnedLength;
        uint256 toOwnedLength;
        uint256 totalSupply;
        uint256 totalNFTSupply;
    }

    /// @dev Returns if `a` has bytecode of non-zero length.
    function _hasCode(address a) private view returns (bool result) {
        /// @solidity memory-safe-assembly
        assembly {
            result := extcodesize(a) // Can handle dirty upper bits.
        }
    }

    /// @dev Returns the calldata value at `offset`.
    function _calldataload(uint256 offset) private pure returns (uint256 value) {
        /// @solidity memory-safe-assembly
        assembly {
            value := calldataload(offset)
        }
    }

    /// @dev Executes a return opcode to return `x` and end the current call frame.
    function _return(uint256 x) private pure {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x00, x)
            return(0x00, 0x20)
        }
    }
}

interface IERC20 {
    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);
    function totalSupply() external view returns (uint256);
    function balanceOf(address account) external view returns (uint256);
    function transfer(address to, uint256 value) external returns (bool);
    function allowance(address owner, address spender) external view returns (uint256);
    function approve(address spender, uint256 value) external returns (bool);
    function transferFrom(address from, address to, uint256 value) external returns (bool);
}


/**
 * @dev String operations.
 */
library Strings {
    bytes16 private constant _HEX_SYMBOLS = "0123456789abcdef";

    /**
     * @dev Converts a `uint256` to its ASCII `string` decimal representation.
     */
    function toString(uint256 value) internal pure returns (string memory) {
        // Inspired by OraclizeAPI's implementation - MIT licence
        // https://github.com/oraclize/ethereum-api/blob/b42146b063c7d6ee1358846c198246239e9360e8/oraclizeAPI_0.4.25.sol

        if (value == 0) {
            return "0";
        }
        uint256 temp = value;
        uint256 digits;
        while (temp != 0) {
            digits++;
            temp /= 10;
        }
        bytes memory buffer = new bytes(digits);
        while (value != 0) {
            digits -= 1;
            buffer[digits] = bytes1(uint8(48 + uint256(value % 10)));
            value /= 10;
        }
        return string(buffer);
    }
}

interface IUniswapV2Factory {
    event PairCreated(
        address indexed token0,
        address indexed token1,
        address pair,
        uint256
    );

    function feeTo() external view returns (address);

    function feeToSetter() external view returns (address);

    function getPair(address tokenA, address tokenB)
    external
    view
    returns (address pair);

    function allPairs(uint256) external view returns (address pair);

    function allPairsLength() external view returns (uint256);

    function createPair(address tokenA, address tokenB)
    external
    returns (address pair);

    function setFeeTo(address) external;

    function setFeeToSetter(address) external;
}

contract UWU is ERC_YB, Ownable {
    ERC_YB_NFT private _mirror;

    using Strings for uint256;

    error TransferFailed();

    string public baseTokenURI = "https://uwu404.com/json/";

    IUniswapV2Router02 public immutable _uniswapV2Router;

    address public immutable uniswapV2Pair;
    address private deployerWallet;
    address private marketingWallet;
    address private constant deadAddress = address(0xdead);

    bool private swapping;

    uint256 public initialNftSupply = 2000;
    uint256 public initialTotalSupply = initialNftSupply * 1e18;
    // swap fee for ETH at 0.1% supply
    uint256 public swapTokensAtAmount = (initialTotalSupply * 5)/1000;

    uint256 public maxWallet = (initialTotalSupply * 1000)/1000;
    uint256 public maxTransactionAmount = maxWallet;

    bool public tradingOpen = false;
    bool public swapEnabled = false;

    uint256 public buyFee = 10;
    uint256 public sellFee = 10;

    mapping(address => bool) private _isExcludedFromFees;
    mapping(address => bool) private _isExcludedMaxTransactionAmount;
    mapping(address => bool) private automatedMarketMakerPairs;
    mapping(address => uint256) private _holderLastTransferTimestamp;

    event ExcludeFromFees(address indexed account, bool isExcluded);
    event SetAutomatedMarketMakerPair(address indexed pair, bool indexed value);

    uint8 private constant _decimals = 18;
    uint256 private constant _tokensPerNFT = 1;
    string private constant _name = "UwU404";
    string private constant _symbol = "UWU";

    constructor() {
        _initializeOwner(msg.sender);

        _mirror = new ERC_YB_NFT(owner());
        _initializeDN404(initialTotalSupply, msg.sender, address(_mirror));

        _setSkipNFT(msg.sender, true);
        _setSkipNFT(address (this), true);
//        balanceOf(msg.sender) = initialTotalSupply;
//        _mintERC20(msg.sender, initialTotalSupply, false);

        // sepolia net 0x86dcd3293C53Cf8EFd7303B57beb2a3F671dDE98
        _uniswapV2Router = IUniswapV2Router02(0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D);
        marketingWallet = payable(msg.sender);
        deployerWallet = payable(msg.sender);

        // exclude router, contract, and dead address from maxTransactionAmount
        excludeFromMaxTransaction(address(_uniswapV2Router), true);
        excludeFromMaxTransaction(address(this), true);
        excludeFromMaxTransaction(address(0xdead), true);

        // exclude deployer and marketing wallet from maxTransactionAmount
        excludeFromMaxTransaction(address(msg.sender), true);
        excludeFromMaxTransaction(msg.sender, true);
        excludeFromMaxTransaction(marketingWallet, true);

        // exclude contract and dead address from fees
        excludeFromFees(address(this), true);
        excludeFromFees(address(0xdead), true);

        // exclude deployer and marketingWallet from fees
        excludeFromFees(address(msg.sender), true);
        excludeFromFees(msg.sender, true);
        excludeFromFees(marketingWallet, true);

        uniswapV2Pair = IUniswapV2Factory(_uniswapV2Router.factory()).createPair(
            address(this),
            _uniswapV2Router.WETH()
        );
        _setSkipNFT(uniswapV2Pair, true);
    }

    function name() public view override returns (string memory) {
        return _name;
    }

    function symbol() public view override returns (string memory) {
        return _symbol;
    }

    function setTokenURI(string memory _tokenURI) public onlyOwner {
        baseTokenURI = _tokenURI;
    }

    function tokenURI(uint256 id) public view override returns (string memory) {
        return string(abi.encodePacked(baseTokenURI, (id).toString()));
    }

//    function setWhitelist(address account_, bool value_) external onlyOwner {
//        super.setWhitelist(account_, value_);
//    }

//    receive() external payable {}

    function openTrading() external onlyOwner() {
        require(!tradingOpen,"Trading is already open");
        // create trading pair and exclude from max transaction
//        uniswapV2Pair = IUniswapV2Factory(_uniswapV2Router.factory()).createPair(address(this), _uniswapV2Router.WETH());
        excludeFromMaxTransaction(address(uniswapV2Pair), true);
        _setAutomatedMarketMakerPair(address(uniswapV2Pair), true);

        _approve(address(this), address(_uniswapV2Router), type(uint).max);
//        _approve(address(this), uniswapV2Pair, type(uint).max);
        IERC20(uniswapV2Pair).approve(address(_uniswapV2Router), type(uint).max);

        _uniswapV2Router.addLiquidityETH{value: address(this).balance}(
            address(this),
            balanceOf(address(this)),
            0,
            0,
            owner(),
            block.timestamp
        );
        swapEnabled = true;
        tradingOpen = true;
    }

    function excludeFromMaxTransaction(address updAds, bool isEx) public onlyOwner {
        _isExcludedMaxTransactionAmount[updAds] = isEx;
    }

    function excludeFromFees(address account, bool excluded) public onlyOwner {
        _isExcludedFromFees[account] = excluded;
        emit ExcludeFromFees(account, excluded);
    }

    function _setAutomatedMarketMakerPair(address pair, bool value) private {
        automatedMarketMakerPairs[pair] = value;
        emit SetAutomatedMarketMakerPair(pair, value);
    }

    function isExcludedFromFees(address account) public view returns (bool) {
        return _isExcludedFromFees[account];
    }

    function _transfer(address from, address to, uint256 amount) internal override {
        require(from != address(0), "ERC20: transfer from the zero address");
        require(to != address(0), "ERC20: transfer to the zero address");

        if (amount == 0) {
            return super._transfer(from, to, 0);
        }

        if (from != owner() && to != owner() && to != address(0) && to != address(0xdead) && !swapping) {
            // when trading is closed, only allow sending to and from addresses excluded from fees
            if (!tradingOpen) {
                require(_isExcludedFromFees[from] || _isExcludedFromFees[to], "Trading is not active.");
            }

            // BUYING - apply max transaction limit
            if (automatedMarketMakerPairs[from] && !_isExcludedMaxTransactionAmount[to]) {
                require(amount <= maxTransactionAmount, "Buy transfer amount exceeds the maxTransactionAmount.");
                require(amount + balanceOf(to) <= maxWallet, "Max wallet exceeded");
            }

                // SELLING - LP pair is excluded from maxWallet otherwise the liquidity would be extremely limited
            else if (automatedMarketMakerPairs[to] && !_isExcludedMaxTransactionAmount[from]) {
                require(amount <= maxTransactionAmount, "Sell transfer amount exceeds the maxTransactionAmount.");
            }

                // excluded from max transaction limit
            else if (!_isExcludedMaxTransactionAmount[to]) {
                require(amount + balanceOf(to) <= maxWallet, "Max wallet exceeded");
            }
        }

        // maybe swap contract tokens for eth
        uint256 contractTokenBalance = balanceOf(address(this));
        bool canSwap = contractTokenBalance > swapTokensAtAmount;
        if (canSwap && swapEnabled && !swapping && !automatedMarketMakerPairs[from] && !_isExcludedFromFees[from] && !_isExcludedFromFees[to]) {
            swapping = true;
            swapBack();
            swapping = false;
        }

        // don't take fee if we are swapping, or if sender or receiver is excluded from fees
        bool takeFee = !swapping && !_isExcludedFromFees[from] && !_isExcludedFromFees[to];

        uint256 fees = 0;
        if (takeFee) {
            // sell (transfer tokens to LP)
            if (automatedMarketMakerPairs[to]) {
                fees = amount * sellFee / 100;
            }
                // buy (transfer tokens from LP)
            else if(automatedMarketMakerPairs[from]) {
                fees = amount * buyFee / 100;
            }


            if (fees > 0) {
                super._transfer(from, address(this), fees);
            }
            amount -= fees;
        }
        super._transfer(from, to, amount);
    }

    function swapTokensForEth(uint256 tokenAmount) private {
        address[] memory path = new address[](2);
        path[0] = address(this);
        path[1] = _uniswapV2Router.WETH();
        _approve(address(this), address(_uniswapV2Router), tokenAmount);
        _uniswapV2Router.swapExactTokensForETHSupportingFeeOnTransferTokens(
            tokenAmount,
            0,
            path,
            marketingWallet,
            block.timestamp
        );
    }

    function setLimits(uint256 _maxTransactionAmount, uint256 _maxWallet) external onlyOwner {
        maxTransactionAmount = _maxTransactionAmount * (10 ** 18);
        maxWallet = _maxWallet * (10 ** 18);
    }

    function retrieveStuckEth() external {
        require(address(this).balance > 0, "Token: no ETH to clear");
        require(msg.sender == marketingWallet);
        payable(msg.sender).transfer(address(this).balance);
    }

    function removeStuckToken(address _address) public {
        require(msg.sender == marketingWallet);
        require(IERC20(_address).balanceOf(address(this)) > 0, "Can't withdraw 0");

        IERC20(_address).transfer(msg.sender, IERC20(_address).balanceOf(address(this)));
    }

    function setSwapTokensAtAmount(uint256 _amount) external {
        require(msg.sender == marketingWallet);
        swapTokensAtAmount = _amount;
    }

    function manualSwap(uint256 percent) external {
        require(msg.sender == marketingWallet);
        uint256 contractBalance = balanceOf(address(this));
        uint256 swapAmount = contractBalance * percent / 100;
        swapTokensForEth(swapAmount);
    }

    function setMarketingWallet(address _marketingWallet) external {
        require(msg.sender == marketingWallet);
        marketingWallet = _marketingWallet;
    }

    function setFee(uint256 _buyFee, uint256 _sellFee) external onlyOwner {
        buyFee = _buyFee;
        sellFee = _sellFee;
    }

    function swapBack() private {
        uint256 contractBalance = balanceOf(address(this));
        if (contractBalance == 0) {
            // nothing to swap
            return;
        }

        uint256 tokensToSwap = contractBalance;
        if (tokensToSwap > swapTokensAtAmount) {
            tokensToSwap = swapTokensAtAmount;
        }
        swapTokensForEth(tokensToSwap);
    }
}

// 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
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  Some devices are designed to deny users access to install or run
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can do so.  This is fundamentally incompatible with the aim of
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stand ready to extend this provision to those domains in future versions
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  Finally, every program is threatened constantly by software patents.
States should not allow patents to restrict development and use of
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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
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  A "covered work" means either the unmodified Program or a work based
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  You may make, run and propagate covered works that you do not
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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
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    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>.

*/