Contract Source Code:

//SPDX-License-Identifier: UNLICENSED

pragma solidity ^0.8.16;

import "@openzeppelin/contracts/interfaces/IERC20.sol";
import "@openzeppelin/contracts/utils/math/SafeMath.sol";
import "@uniswap/v2-core/contracts/interfaces/IUniswapV2Factory.sol";
import "@uniswap/v2-periphery/contracts/interfaces/IUniswapV2Router02.sol";
import "@uniswap/v2-core/contracts/interfaces/IUniswapV2Pair.sol";
import "@openzeppelin/contracts/access/Ownable.sol";

library Roles {
    struct Role {
        mapping(address => bool) bearer;
    }

    /**
     * @dev Give an account access to this role.
     */
    function add(Role storage role, address account) internal {
        require(!has(role, account), "Roles: account already has role");
        role.bearer[account] = true;
    }

    /**
     * @dev Remove an account's access to this role.
     */
    function remove(Role storage role, address account) internal {
        require(has(role, account), "Roles: account does not have role");
        role.bearer[account] = false;
    }

    /**
     * @dev Check if an account has this role.
     * @return bool
     */
    function has(Role storage role, address account)
        internal
        view
        returns (bool)
    {
        require(account != address(0), "Roles: account is the zero address");
        return role.bearer[account];
    }
}

abstract contract ERC20Detailed is IERC20 {
    string private _name;
    string private _symbol;
    uint8 private _decimals;

    constructor(
        string memory name_,
        string memory symbol_,
        uint8 decimals_
    ) {
        _name = name_;
        _symbol = symbol_;
        _decimals = decimals_;
    }

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

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

    function decimals() public view returns (uint8) {
        return _decimals;
    }
}

contract DVM is ERC20Detailed, Ownable {
    struct Fee {
        uint16 liquidity;
        uint16 treasury;
    }

    using SafeMath for uint256;

    event LogRebase(uint256 indexed epoch, uint256 totalSupply);
    event NewNextRebase(uint256 nextRebase);
    event NewRewardYield(uint256 _rewardYield, uint256 _rewardYieldDenominator);
    event NewAutoRebase(bool _autoRebase);
    event NewMaxWalletEnable(bool _isMaxWalletEnabled);
    event NewRebaseFrequency(uint256 _rebaseFrequency);
    event DustSwiped(address _receiver, uint256 balance);
    event ManualRebase();
    event NewLPSet(address _address);
    event InitialDistributionFinished();
    event AddressExemptedFromTransferLock(address _addr);
    event AddressExemptedFromFee(address _addr);
    event NewSwapBackSet(bool _enabled, uint256 _num, uint256 _denom);
    event NewTargetLiquiditySet(uint256 target, uint256 accuracy);
    event NewFeeReceiversSet(
        address _autoLiquidityReceiver,
        address _treasuryReceiver
    );
    event NewBuyFeesSet(
        uint256 _liquidityFee,
        uint256 _treasuryFee,
        uint256 _feeDenominator
    );
    event NewSellFeesSet(
        uint256 _liquidityFee,
        uint256 _treasuryFee,
        uint256 _feeDenominator
    );

    IUniswapV2Pair public pairContract;

    bool public initialDistributionFinished;

    mapping(address => bool) internal allowTransfer;
    mapping(address => bool) public _isFeeExempt;
    mapping(address => bool) public _isLimitExempt;

    modifier initialDistributionLock() {
        require(
            initialDistributionFinished ||
                msg.sender == owner() ||
                allowTransfer[msg.sender],
            "Initial distribution lock"
        );
        _;
    }

    modifier validRecipient(address to) {
        require(to != address(0x0), "Zero address");
        _;
    }

    uint256 private constant DECIMALS = 18;
    uint256 private constant MAX_UINT256 = type(uint256).max;
    uint256 private constant INITIAL_FRAGMENTS_SUPPLY = 10000 * 10**DECIMALS;

    Fee public buyFee;
    Fee public sellFee;

    uint256 private totalBuyFee;
    uint256 private totalSellFee;

    uint256 public feeDenominator = 1000;
    uint256 public rewardYield = 1;
    uint256 public rewardYieldDenominator = 100000000000;
    uint256 public rebaseFrequency = 1 days;
    uint256 public nextRebase = block.timestamp + rebaseFrequency;
    bool public autoRebase = true;

    address internal constant DEAD = 0x000000000000000000000000000000000000dEaD;
    address internal constant ZERO = 0x0000000000000000000000000000000000000000;

    address public autoLiquidityReceiver;
    address public treasuryReceiver;

    uint256 private targetLiquidity = 50;
    uint256 private targetLiquidityDenominator = 100;

    IUniswapV2Router02 public immutable router;

    bool public swapEnabled = true;
    bool internal inSwap;
    modifier swapping() {
        inSwap = true;
        _;
        inSwap = false;
    }

    uint256 private constant TOTAL_GONS =
        MAX_UINT256 - (MAX_UINT256 % INITIAL_FRAGMENTS_SUPPLY);

    uint256 private constant MAX_SUPPLY = 20000 * 10**DECIMALS;
    uint256 private gonSwapThreshold = TOTAL_GONS / 5000;
    uint256 private maxWalletDivisor = 100;
    bool public isMaxWalletEnabled = true;

    uint256 private _totalSupply;
    uint256 private _gonsPerFragment;
    mapping(address => uint256) private _gonBalances;

    mapping(address => mapping(address => uint256)) private _allowedFragments;

    constructor(
        address _router,
        address _autoLiquidityReceiver,
        address _treasuryReceiver
    ) ERC20Detailed("DVM", "DVM", uint8(DECIMALS)) {
        router = IUniswapV2Router02(_router);

        address _pair = IUniswapV2Factory(router.factory()).createPair(
            router.WETH(),
            address(this)
        );

        buyFee = Fee(15, 15);
        totalBuyFee = 30;
        sellFee = Fee(15, 15);
        totalSellFee = 30;

        autoLiquidityReceiver = _autoLiquidityReceiver;
        treasuryReceiver = _treasuryReceiver;

        _allowedFragments[address(this)][address(_router)] = type(uint256).max;
        pairContract = IUniswapV2Pair(_pair);

        _totalSupply = INITIAL_FRAGMENTS_SUPPLY;
        _gonBalances[treasuryReceiver] = TOTAL_GONS;
        _gonsPerFragment = TOTAL_GONS.div(_totalSupply);

        initialDistributionFinished = false;
        _isFeeExempt[treasuryReceiver] = true;
        _isFeeExempt[address(this)] = true;

        emit Transfer(address(0x0), treasuryReceiver, _totalSupply);
    }

    function setNextRebase(uint256 _nextRebase) external onlyOwner {
        nextRebase = _nextRebase;

        emit NewNextRebase(_nextRebase);
    }

    function setRewardYield(
        uint256 _rewardYield,
        uint256 _rewardYieldDenominator
    ) external onlyOwner {
        rewardYield = _rewardYield;
        rewardYieldDenominator = _rewardYieldDenominator;

        emit NewRewardYield(_rewardYield, _rewardYieldDenominator);
    }

    function setLimitExempt(address user, bool status) external onlyOwner {
        _isLimitExempt[user] = status;
    }

    function setAutoRebase(bool _autoRebase) external onlyOwner {
        autoRebase = _autoRebase;

        emit NewAutoRebase(_autoRebase);
    }

    function setRebaseFrequency(uint256 _rebaseFrequency) external onlyOwner {
        rebaseFrequency = _rebaseFrequency;

        emit NewRebaseFrequency(_rebaseFrequency);
    }

    function shouldRebase() public view returns (bool) {
        return nextRebase <= block.timestamp;
    }

    function swipe(address _receiver) external onlyOwner {
        uint256 balance = address(this).balance;
        payable(_receiver).transfer(balance);

        emit DustSwiped(_receiver, balance);
    }

    function coreRebase(uint256 epoch, int256 supplyDelta)
        private
        returns (uint256)
    {
        if (supplyDelta == 0) {
            emit LogRebase(epoch, _totalSupply);
            return _totalSupply;
        }

        if (supplyDelta < 0) {
            _totalSupply = _totalSupply.sub(uint256(-supplyDelta));
        } else {
            _totalSupply = _totalSupply.add(uint256(supplyDelta));
        }

        if (_totalSupply > MAX_SUPPLY) {
            _totalSupply = MAX_SUPPLY;
        }

        _gonsPerFragment = TOTAL_GONS.div(_totalSupply);
        pairContract.sync();

        emit LogRebase(epoch, _totalSupply);
        return _totalSupply;
    }

    function _rebase() private {
        if (!inSwap) {
            uint256 epoch = block.timestamp;
            uint256 circulatingSupply = getCirculatingSupply();
            int256 supplyDelta = int256(
                circulatingSupply.mul(rewardYield).div(rewardYieldDenominator)
            );

            coreRebase(epoch, supplyDelta);
            nextRebase = epoch + rebaseFrequency;
        }
    }

    function rebase() external onlyOwner {
        require(!inSwap && shouldRebase(), "Try again");
        _rebase();

        emit ManualRebase();
    }

    function totalSupply() external view override returns (uint256) {
        return _totalSupply;
    }

    function transfer(address to, uint256 value)
        external
        override
        validRecipient(to)
        initialDistributionLock
        returns (bool)
    {
        _transferFrom(msg.sender, to, value);
        return true;
    }

    function setLP(address _address) external onlyOwner {
        pairContract = IUniswapV2Pair(_address);
        _isFeeExempt[_address];

        emit NewLPSet(_address);
    }

    function setMaxWallet(uint256 divisor) external onlyOwner {
        maxWalletDivisor = divisor;
    }

    function allowance(address owner_, address spender)
        public
        view
        override
        returns (uint256)
    {
        return _allowedFragments[owner_][spender];
    }

    function balanceOf(address who) public view override returns (uint256) {
        return _gonBalances[who].div(_gonsPerFragment);
    }

    function scaledBalanceOf(address who) external view returns (uint256) {
        return _gonBalances[who];
    }

    function _basicTransfer(
        address from,
        address to,
        uint256 amount
    ) internal returns (bool) {
        uint256 gonAmount = amount.mul(_gonsPerFragment);
        _gonBalances[from] = _gonBalances[from].sub(gonAmount);
        _gonBalances[to] = _gonBalances[to].add(gonAmount);
        return true;
    }

    function _transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) internal returns (bool) {
        if (inSwap) {
            return _basicTransfer(sender, recipient, amount);
        }

        uint256 gonAmount = amount.mul(_gonsPerFragment);

        if (shouldSwapBack()) {
            swapBack();
        }

        if (
            recipient != address(pairContract) &&
            !_isLimitExempt[recipient] &&
            isMaxWalletEnabled
        ) {
            uint256 max = getMaxWallet();
            require(
                balanceOf(recipient) + amount <= max,
                "Balance exceeds max wallet limit"
            );
        }

        _gonBalances[sender] = _gonBalances[sender].sub(gonAmount);

        uint256 gonAmountReceived = shouldTakeFee(sender, recipient)
            ? takeFee(sender, recipient, gonAmount)
            : gonAmount;

        _gonBalances[recipient] = _gonBalances[recipient].add(
            gonAmountReceived
        );

        emit Transfer(
            sender,
            recipient,
            gonAmountReceived.div(_gonsPerFragment)
        );

        if (shouldRebase() && autoRebase) {
            _rebase();
        }

        return true;
    }

    function transferFrom(
        address from,
        address to,
        uint256 value
    ) external override validRecipient(to) returns (bool) {
        if (_allowedFragments[from][msg.sender] != ~uint256(0)) {
            _allowedFragments[from][msg.sender] = _allowedFragments[from][
                msg.sender
            ].sub(value, "Insufficient Allowance");
        }

        _transferFrom(from, to, value);
        return true;
    }

    function swapBack() internal swapping {
        uint256 dynamicLiquidityFee = isOverLiquified(
            targetLiquidity,
            targetLiquidityDenominator
        )
            ? 0
            : buyFee.liquidity + sellFee.liquidity;
        uint256 contractTokenBalance = _gonBalances[address(this)].div(
            _gonsPerFragment
        );
        uint256 amountToLiquify = contractTokenBalance
            .mul(dynamicLiquidityFee)
            .div(totalBuyFee + totalSellFee)
            .div(2);
        uint256 amountToSwap = contractTokenBalance.sub(amountToLiquify);

        address[] memory path = new address[](2);
        path[0] = address(this);
        path[1] = router.WETH();

        uint256 balanceBefore = address(this).balance;
        router.swapExactTokensForETHSupportingFeeOnTransferTokens(
            amountToSwap,
            0,
            path,
            address(this),
            block.timestamp + 100
        );
        uint256 amountETH = address(this).balance.sub(balanceBefore);
        uint256 totalETHFee = (totalBuyFee + totalSellFee).sub(
            dynamicLiquidityFee.div(2)
        );

        uint256 amountETHLiquidity = amountETH
            .mul(dynamicLiquidityFee)
            .div(totalETHFee)
            .div(2);

        uint256 amountETHTreasury = amountETH
            .mul(buyFee.treasury + sellFee.treasury)
            .div(totalETHFee);

        if (amountETHTreasury > 0) {
            (bool success, ) = treasuryReceiver.call{value: amountETHTreasury}(
                ""
            );
            require(success, "ETH transfer failed");
        }

        if (amountToLiquify > 0) {
            router.addLiquidityETH{value: amountETHLiquidity}(
                address(this),
                amountToLiquify,
                0,
                0,
                autoLiquidityReceiver,
                block.timestamp + 100
            );
        }
    }

    function takeFee(
        address sender,
        address recipient,
        uint256 gonAmount
    ) internal returns (uint256) {
        uint256 _totalFee;
        if (sender == address(pairContract)) {
            _totalFee = totalBuyFee;
        } else if (recipient == address(pairContract)) {
            _totalFee = totalSellFee;
        }

        if (_totalFee > 0) {
            uint256 feeAmount = gonAmount.mul(_totalFee).div(feeDenominator);

            _gonBalances[address(this)] = _gonBalances[address(this)].add(
                feeAmount
            );

            emit Transfer(
                sender,
                address(this),
                feeAmount.div(_gonsPerFragment)
            );
            return gonAmount.sub(feeAmount);
        }

        return gonAmount;
    }

    function decreaseAllowance(address spender, uint256 subtractedValue)
        external
        initialDistributionLock
        returns (bool)
    {
        uint256 oldValue = _allowedFragments[msg.sender][spender];
        if (subtractedValue >= oldValue) {
            _allowedFragments[msg.sender][spender] = 0;
        } else {
            _allowedFragments[msg.sender][spender] = oldValue.sub(
                subtractedValue
            );
        }
        emit Approval(
            msg.sender,
            spender,
            _allowedFragments[msg.sender][spender]
        );
        return true;
    }

    function increaseAllowance(address spender, uint256 addedValue)
        external
        initialDistributionLock
        returns (bool)
    {
        _allowedFragments[msg.sender][spender] = _allowedFragments[msg.sender][
            spender
        ].add(addedValue);
        emit Approval(
            msg.sender,
            spender,
            _allowedFragments[msg.sender][spender]
        );
        return true;
    }

    function approve(address spender, uint256 value)
        external
        override
        validRecipient(spender)
        initialDistributionLock
        returns (bool)
    {
        _allowedFragments[msg.sender][spender] = value;
        emit Approval(msg.sender, spender, value);
        return true;
    }

    function checkFeeExempt(address _addr) external view returns (bool) {
        return _isFeeExempt[_addr];
    }

    function setInitialDistributionFinished() external onlyOwner {
        initialDistributionFinished = true;

        emit InitialDistributionFinished();
    }

    function enableTransfer(address _addr) external onlyOwner {
        allowTransfer[_addr] = true;

        emit AddressExemptedFromTransferLock(_addr);
    }

    function setFeeExempt(address _addr) external onlyOwner {
        _isFeeExempt[_addr] = true;

        emit AddressExemptedFromFee(_addr);
    }

    function shouldTakeFee(address from, address to)
        internal
        view
        returns (bool)
    {
        return ((address(pairContract) == from ||
            address(pairContract) == to) &&
            (!_isFeeExempt[from] && !_isFeeExempt[to]));
    }

    function setSwapBackSettings(
        bool _enabled,
        uint256 _num,
        uint256 _denom
    ) external onlyOwner {
        swapEnabled = _enabled;
        gonSwapThreshold = TOTAL_GONS.div(_denom).mul(_num);

        emit NewSwapBackSet(_enabled, _num, _denom);
    }

    function shouldSwapBack() internal view returns (bool) {
        return
            msg.sender != address(pairContract) &&
            !inSwap &&
            swapEnabled &&
            _gonBalances[address(this)] >= gonSwapThreshold;
    }

    function setMaxWalletEnable(bool _isMaxWalletEnabled) external onlyOwner {
        isMaxWalletEnabled = _isMaxWalletEnabled;

        emit NewMaxWalletEnable(_isMaxWalletEnabled);
    }

    function getCirculatingSupply() public view returns (uint256) {
        return
            (TOTAL_GONS.sub(_gonBalances[DEAD]).sub(_gonBalances[ZERO])).div(
                _gonsPerFragment
            );
    }

    function setTargetLiquidity(uint256 target, uint256 accuracy)
        external
        onlyOwner
    {
        targetLiquidity = target;
        targetLiquidityDenominator = accuracy;

        emit NewTargetLiquiditySet(target, accuracy);
    }

    function isNotInSwap() external view returns (bool) {
        return !inSwap;
    }

    function checkSwapThreshold() external view returns (uint256) {
        return gonSwapThreshold.div(_gonsPerFragment);
    }

    function getMaxWallet() public view returns (uint256 amount) {
        amount = getCirculatingSupply() / maxWalletDivisor;
    }

    function manualSync() external {
        pairContract.sync();
    }

    function setFeeReceivers(
        address _autoLiquidityReceiver,
        address _treasuryReceiver
    ) external onlyOwner {
        autoLiquidityReceiver = _autoLiquidityReceiver;
        treasuryReceiver = _treasuryReceiver;

        emit NewFeeReceiversSet(_autoLiquidityReceiver, _treasuryReceiver);
    }

    function setBuyFees(
        uint16 _liquidityFee,
        uint16 _treasuryFee,
        uint256 _feeDenominator
    ) external onlyOwner {
        buyFee = Fee(_liquidityFee, _treasuryFee);
        feeDenominator = _feeDenominator;
        totalBuyFee = _liquidityFee + _treasuryFee;

        emit NewBuyFeesSet(_liquidityFee, _treasuryFee, _feeDenominator);
    }

    function setSellFees(
        uint16 _liquidityFee,
        uint16 _treasuryFee,
        uint256 _feeDenominator
    ) external onlyOwner {
        sellFee = Fee(_liquidityFee, _treasuryFee);
        feeDenominator = _feeDenominator;
        totalSellFee = _liquidityFee + _treasuryFee;

        emit NewSellFeesSet(_liquidityFee, _treasuryFee, _feeDenominator);
    }

    function getLiquidityBacking(uint256 accuracy)
        public
        view
        returns (uint256)
    {
        uint256 liquidityBalance = _gonBalances[address(pairContract)].div(
            _gonsPerFragment
        );
        return
            accuracy.mul(liquidityBalance.mul(2)).div(getCirculatingSupply());
    }

    function isOverLiquified(uint256 target, uint256 accuracy)
        public
        view
        returns (bool)
    {
        return getLiquidityBacking(accuracy) > target;
    }

    receive() external payable {
        this;
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (interfaces/IERC20.sol)

pragma solidity ^0.8.0;

import "../token/ERC20/IERC20.sol";

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (utils/math/SafeMath.sol)

pragma solidity ^0.8.0;

// CAUTION
// This version of SafeMath should only be used with Solidity 0.8 or later,
// because it relies on the compiler's built in overflow checks.

/**
 * @dev Wrappers over Solidity's arithmetic operations.
 *
 * NOTE: `SafeMath` is generally not needed starting with Solidity 0.8, since the compiler
 * now has built in overflow checking.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            uint256 c = a + b;
            if (c < a) return (false, 0);
            return (true, c);
        }
    }

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

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

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

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

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

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

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

    /**
     * @dev Returns the integer division of two unsigned integers, reverting on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator.
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return a / b;
    }

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

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

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

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

pragma solidity >=0.6.2;

import './IUniswapV2Router01.sol';

interface IUniswapV2Router02 is IUniswapV2Router01 {
    function removeLiquidityETHSupportingFeeOnTransferTokens(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external returns (uint amountETH);
    function removeLiquidityETHWithPermitSupportingFeeOnTransferTokens(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external returns (uint amountETH);

    function swapExactTokensForTokensSupportingFeeOnTransferTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external;
    function swapExactETHForTokensSupportingFeeOnTransferTokens(
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external payable;
    function swapExactTokensForETHSupportingFeeOnTransferTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external;
}

// 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);
    }
}

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;
}

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;
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

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

    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

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

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

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

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

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

pragma solidity >=0.6.2;

interface IUniswapV2Router01 {
    function factory() external pure returns (address);
    function WETH() external pure returns (address);

    function addLiquidity(
        address tokenA,
        address tokenB,
        uint amountADesired,
        uint amountBDesired,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) external returns (uint amountA, uint amountB, uint liquidity);
    function addLiquidityETH(
        address token,
        uint amountTokenDesired,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external payable returns (uint amountToken, uint amountETH, uint liquidity);
    function removeLiquidity(
        address tokenA,
        address tokenB,
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline
    ) external returns (uint amountA, uint amountB);
    function removeLiquidityETH(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline
    ) external returns (uint amountToken, uint amountETH);
    function removeLiquidityWithPermit(
        address tokenA,
        address tokenB,
        uint liquidity,
        uint amountAMin,
        uint amountBMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external returns (uint amountA, uint amountB);
    function removeLiquidityETHWithPermit(
        address token,
        uint liquidity,
        uint amountTokenMin,
        uint amountETHMin,
        address to,
        uint deadline,
        bool approveMax, uint8 v, bytes32 r, bytes32 s
    ) external returns (uint amountToken, uint amountETH);
    function swapExactTokensForTokens(
        uint amountIn,
        uint amountOutMin,
        address[] calldata path,
        address to,
        uint deadline
    ) external returns (uint[] memory amounts);
    function swapTokensForExactTokens(
        uint amountOut,
        uint amountInMax,
        address[] calldata path,
        address to,
        uint deadline
    ) external returns (uint[] memory amounts);
    function swapExactETHForTokens(uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        payable
        returns (uint[] memory amounts);
    function swapTokensForExactETH(uint amountOut, uint amountInMax, address[] calldata path, address to, uint deadline)
        external
        returns (uint[] memory amounts);
    function swapExactTokensForETH(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline)
        external
        returns (uint[] memory amounts);
    function swapETHForExactTokens(uint amountOut, address[] calldata path, address to, uint deadline)
        external
        payable
        returns (uint[] memory amounts);

    function quote(uint amountA, uint reserveA, uint reserveB) external pure returns (uint amountB);
    function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut) external pure returns (uint amountOut);
    function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut) external pure returns (uint amountIn);
    function getAmountsOut(uint amountIn, address[] calldata path) external view returns (uint[] memory amounts);
    function getAmountsIn(uint amountOut, address[] calldata path) external view returns (uint[] memory amounts);
}

// 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;
    }
}