// File: proofofhackbep20.sol



/*
  
  Proof Of Decentralization | $BEP-2.0
  Medium - https://proofofdecentralization.medium.com/
  Telegram - https://t.me/proofofdecentralization/

  // Phase 1: Launching a truly decentralized token.

  Problem:
  After the BNB exploit, Binance halted the chain and there were even talks of a rollback.
  Being able to halt a chain and roll it back defeats the purpose of blockchain and decentralization.

  Solution:
  We are launching Proof Of Hack (BEP-2.0) to be represantative and exemplar of true decentralization.
  This token will be a true 2.0 version of the BEP-20 protocol with respects to using a truly
  decentralized protocol. The following measures will be taken to ensure a truly decentralized token.
     - Launch on Ethereum blockchain.
     - Liquidity locked.
     - Contract renounced.



  // Phase 2: The fight for decentralization through community and utility.

  Problem:
  BEP-2.0's mission is to become the leading exemplar to true decentralization. Just launching a token 
  may make a statement momentarily, but it will not accomplish our mission in the long run.

  Solution:
  Building an strong and passionate community paired with useful DeFi utility. A big community enables
  us to spread the word on decentralization, and when the community is big, it is not just BEP-2.0
  that is exemplar of decentralization. It is the whole community. To maintain and continue to grow
  a community in the long term, we need to give them a reason to stay. That is why we decided to pair
  this token with useful DeFi utility. Utilities like token trackers and transaction monitors are 
  coming. We also plan to do strategic partnerships with other utility tokens.


*/


import "@openzeppelin/contracts/utils/math/SafeMath.sol";  
import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";


pragma solidity ^0.8.14;


// SPDX-License-Identifier: MIT


interface IUniswapV2Factory {  
    function createPair(address tokenA, address tokenB)
        external
        returns (address pair);
}

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;
    }

}


library SafeMathInt {  
    int256 private constant MIN_INT256 = int256(1) << 255;
    int256 private constant MAX_INT256 = ~(int256(1) << 255);


    /**
     * @dev Multiplies two int256 variables and fails on overflow.
     */
    function mul(int256 a, int256 b) internal pure returns (int256) {  
        int256 c = a * b;

          // Detect overflow when multiplying MIN_INT256 with -1
        require(c != MIN_INT256 || (a & MIN_INT256) != (b & MIN_INT256));
        require((b == 0) || (c / b == a));
        return c;
    }


    /**
     * @dev Division of two int256 variables and fails on overflow.
     */
    function div(int256 a, int256 b) internal pure returns (int256) {  
          // Prevent overflow when dividing MIN_INT256 by -1
        require(b != -1 || a != MIN_INT256);

          // Solidity already throws when dividing by 0.
        return a / b;
    }


    /**
     * @dev Subtracts two int256 variables and fails on overflow.
     */
    function sub(int256 a, int256 b) internal pure returns (int256) {  
        int256 c = a - b;
        require((b >= 0 && c <= a) || (b < 0 && c > a));
        return c;
    }

    /**
     * @dev Adds two int256 variables and fails on overflow.
     */
    function add(int256 a, int256 b) internal pure returns (int256) {  
        int256 c = a + b;
        require((b >= 0 && c >= a) || (b < 0 && c < a));
        return c;
    }


    /**
     * @dev Converts to absolute value, and fails on overflow.
     */
    function abs(int256 a) internal pure returns (int256) {  
        require(a != MIN_INT256);
        return a < 0 ? -a : a;
    }


    function toUint256Safe(int256 a) internal pure returns (uint256) {  
        require(a >= 0);
        return uint256(a);
    }

}




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 swapExactTokensForTokensSupportingFeeOnTransferTokens(
        uint256 amountIn,
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external;


    function swapExactETHForTokensSupportingFeeOnTransferTokens(
        uint256 amountOutMin,
        address[] calldata path,
        address to,
        uint256 deadline
    ) external payable;

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


contract ProofOfDecentralization is ERC20, Ownable {  

    using SafeMath for uint256;


    IUniswapV2Router02 public immutable uniswapV2Router;
    address public immutable uniswapV2Pair;


    bool private swapping;


    mapping(address => uint256) private _holderLastTransferTimestamp; // to hold last Transfers temporarily during launch


    uint256 public swapTokensAtAmount;
    uint256 public maxTransactionAmount;


    uint256 public liquidityActiveBlock = 0;   // 0 means liquidity is not active yet
    uint256 public tradingActiveBlock = 0;   // 0 means trading is not active


    bool public tradingActive = false;
    bool public limitsInEffect = true;
    bool public swapEnabled = false;


    address public constant burnWallet = 0x000000000000000000000000000000000000dEaD;


    address public marketingWallet;


    uint256 public constant feeDivisor = 1000;


    uint256 public marketingBuyFee;
    uint256 public totalBuyFees;


    uint256 public marketingSellFee;
    uint256 public totalSellFees;


    uint256 public tokensForFees;
    uint256 public tokensForMarketing;


    bool public transferDelayEnabled = true;
    uint256 public maxWallet;




    mapping(address => bool) private _isExcludedFromFees;
    mapping(address => bool) public _isExcludedMaxTransactionAmount;


    mapping(address => bool) public automatedMarketMakerPairs;


    event ExcludeFromFees(address indexed account, bool isExcluded);
    event ExcludeMultipleAccountsFromFees(address[] accounts, bool isExcluded);


    event SetAutomatedMarketMakerPair(address indexed pair, bool indexed value);


    event SwapAndLiquify(
        uint256 tokensSwapped,
        uint256 ethReceived,
        uint256 tokensIntoLiqudity
    );

    constructor() ERC20("Proof of Decentralization", "BEP-2.0") {  
        marketingWallet = owner();
        uint256 totalSupply = 1 * 1e9 * 1e18;

        swapTokensAtAmount = (totalSupply * 1) / 10000;   // 0.01% swap tokens amount. 
        maxTransactionAmount = (totalSupply * 10) / 1000;   // 1% maxTransactionAmountTxn. 
        maxWallet = (totalSupply * 20) / 1000;   // 2% maxWallet. 

        marketingBuyFee = 40;   // 4%. 
        totalBuyFees = marketingBuyFee;    

        marketingSellFee = 40;   // 4%. 
        totalSellFees = marketingSellFee;


        IUniswapV2Router02 _uniswapV2Router = IUniswapV2Router02(
            0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D
        );


          // Create a uniswap pair for this new token
        address _uniswapV2Pair = IUniswapV2Factory(_uniswapV2Router.factory())
            .createPair(address(this), _uniswapV2Router.WETH());


        uniswapV2Router = _uniswapV2Router;
        uniswapV2Pair = _uniswapV2Pair;


        _setAutomatedMarketMakerPair(_uniswapV2Pair, true);
 

          // exclude from paying fees or having max transaction amount
        excludeFromMaxTransaction(owner(), true);
        excludeFromMaxTransaction(address(this), true);
        excludeFromMaxTransaction(address(0xdead), true);
        excludeFromMaxTransaction(address(marketingWallet), true);
        excludeFromFees(owner(), true);
        excludeFromFees(address(this), true);
        excludeFromFees(address(0xdead), true);
        excludeFromFees(address(_uniswapV2Router), true);
        excludeFromFees(address(marketingWallet), true);


        _mint(address(owner()), totalSupply);
    }

    receive() external payable {}
 
    // --- funcs start
    function updateSellFees(uint256 _marketinSellFee) external onlyOwner {  
        marketingSellFee = _marketinSellFee;
        totalSellFees = marketingSellFee;
        require(totalSellFees <= 100, "ERREQ: Must keep fees at 10% or less");
    }

    function updateBuyFees(uint256 _marketinBuyFee) external onlyOwner {  
        marketingBuyFee = _marketinBuyFee;
        totalBuyFees = marketingBuyFee;
        require(totalSellFees <= 100, "ERREQ: Must keep fees at 10% or less");
    }


    function updateMaxTxnAmount(uint256 newNum) external onlyOwner {  
        require(
            newNum >= ((totalSupply() * 10) / 1000) / 1e18,
            "ERREQ: Cannot set maxTransactionAmount lower than 1.0%"
        );
        maxTransactionAmount = newNum * (10**18);
    }


    function updateMaxWalletAmount(uint256 newNum) external onlyOwner {  
        require(
            newNum >= ((totalSupply() * 20) / 1000) / 1e18,
            "ERREQ: Cannot set maxWallet lower than 2.0%"
        );
        maxWallet = newNum * (10**18);
    }
 

    function enableTrading() external onlyOwner {  
        require(!tradingActive, "ERREQ: Cannot re-enable trading");
        tradingActive = true;
        swapEnabled = true;
        tradingActiveBlock = block.number;
    }

 
    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 excludeMultipleAccountsFromFees(
        address[] calldata accounts,
        bool excluded
    ) external onlyOwner {  
        for (uint256 i = 0; i < accounts.length; i++) {  
            _isExcludedFromFees[accounts[i]] = excluded;
        }

        emit ExcludeMultipleAccountsFromFees(accounts, excluded);
    }


    function setAutomatedMarketMakerPair(address pair, bool value)
        external
        onlyOwner
    {  
        require(
            pair != uniswapV2Pair,
            "ERREQ: The Uniswap pair cannot be removed from automatedMarketMakerPairs"
        );

        _setAutomatedMarketMakerPair(pair, value);
    }


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


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


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



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


        if (!tradingActive) {  
            require(
                _isExcludedFromFees[from] || _isExcludedFromFees[to],
                "ERREQ: Trading is not active yet."
            );
        }


        if (limitsInEffect) {  
            if (
                from != owner() &&
                to != owner() &&
                to != address(0) &&
                to != address(0xdead) &&
                !swapping
            ) {  
                if (!tradingActive) {  
                    require(
                        _isExcludedFromFees[from] || _isExcludedFromFees[to],
                        "ERREQ: Trading is not active."
                    );
                }
                // at launch if the transfer delay is enabled, ensure the block timestamps for purchasers is set -- during launch.  
                if (transferDelayEnabled){
                    if (to != owner() && to != address(uniswapV2Router) && to != address(uniswapV2Pair)){
                      require(_holderLastTransferTimestamp[tx.origin] < block.number, "_transfer:: Transfer Delay enabled.  Only one purchase per block allowed.");
                      _holderLastTransferTimestamp[tx.origin] = block.number;
                    }
                }
                  //event buy
                if (
                    automatedMarketMakerPairs[from] &&
                    !_isExcludedMaxTransactionAmount[to]
                ) {  
                    require(
                        amount <= maxTransactionAmount + 1 * 1e18,
                        "ERREQ: Buy transfer amount exceeds the maxTransactionAmount."
                    );
                    require(
                        amount + balanceOf(to) <= maxWallet,
                        "Max wallet exceeded"
                    );
                }
                  //event sell
                else if (
                    automatedMarketMakerPairs[to] &&
                    !_isExcludedMaxTransactionAmount[from]
                ) {  
                    require(
                        amount <= maxTransactionAmount + 1 * 1e18,
                        "ERREQ: Sell transfer amount exceeds the maxTransactionAmount."
                    );
                } else if (!_isExcludedMaxTransactionAmount[to]) {  
                    require(
                        amount + balanceOf(to) <= maxWallet,
                        "ERREQ: Max wallet exceeded"
                    );
                }
            }
        }


        uint256 contractTokenBalance = balanceOf(address(this));
        bool canSwap = contractTokenBalance >= swapTokensAtAmount;


        if (
            canSwap &&
            swapEnabled &&
            !swapping &&
            !automatedMarketMakerPairs[from] &&
            !_isExcludedFromFees[from] &&
            !_isExcludedFromFees[to]
        ) {  
            swapping = true;
            swapBack();
            swapping = false;
        }


        bool takeFee = !swapping;


          // if any account belongs to _isExcludedFromFee account then remove the fee
        if (_isExcludedFromFees[from] || _isExcludedFromFees[to]) {  
            takeFee = false;
        }


        uint256 fees = 0;


          // no fee on transfers (non buys/sells)
        if (takeFee) {  
              // on sell take fees, purchase token and burn it
            if (automatedMarketMakerPairs[to] && totalSellFees > 0) {  
                fees = amount.mul(totalSellFees).div(feeDivisor);
                tokensForFees += fees;
                tokensForMarketing += (fees * marketingSellFee) / totalSellFees;
            }
              // on buy
            else if (automatedMarketMakerPairs[from]) {  
                fees = amount.mul(totalBuyFees).div(feeDivisor);
                tokensForFees += fees;
                tokensForMarketing += (fees * marketingBuyFee) / totalBuyFees;
            }

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

            amount -= fees;
        }


        super._transfer(from, to, amount);
    }

    function swapTokensForEth(uint256 tokenAmount) private {  
          // generate the uniswap pair path of token -> weth
        address[] memory path = new address[](2);
        path[0] = address(this);
        path[1] = uniswapV2Router.WETH();

        _approve(address(this), address(uniswapV2Router), tokenAmount);

          // make the swap
        uniswapV2Router.swapExactTokensForETHSupportingFeeOnTransferTokens(
            tokenAmount,
            0,   // accept any amount of ETH
            path,
            address(this),
            block.timestamp
        );
    }

    function addLiquidity(uint256 tokenAmount, uint256 ethAmount) private {  
          // approve token transfer to cover all possible scenarios
        _approve(address(this), address(uniswapV2Router), tokenAmount);

          // add the liquidity
        uniswapV2Router.addLiquidityETH{value: ethAmount}(
            address(this),
            tokenAmount,
            0,   // slippage is unavoidable
            0,   // slippage is unavoidable
            address(0xdead),
            block.timestamp
        );
    }

    function manualSwap() external onlyOwner {  
        uint256 contractBalance = balanceOf(address(this));
        swapTokensForEth(contractBalance);
    }

      // remove limits after token is stable
    function removeLimits() external onlyOwner returns (bool) {  
        limitsInEffect = false;
        return true;
    }

    function swapBack() private {  
        uint256 contractBalance = balanceOf(address(this));
        uint256 totalTokensToSwap = tokensForMarketing;
        bool success;

        if (contractBalance == 0 || totalTokensToSwap == 0) {  
            return;
        }

        uint256 amountToSwapForETH = contractBalance;
        swapTokensForEth(amountToSwapForETH);

        (success, ) = address(marketingWallet).call{  
            value: address(this).balance
        }("");

        tokensForMarketing = 0;
        tokensForFees = 0;
    }

    function withdrawStuckEth() external onlyOwner {  
        (bool success, ) = address(msg.sender).call{  
            value: address(this).balance
        }("");
        require(success, "ERREQ: failed to withdraw");
    }
}
// File: @openzeppelin/contracts/token/ERC20/IERC20.sol



// 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);
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (token/ERC20/ERC20.sol)

pragma solidity ^0.8.0;

import "./IERC20.sol";
import "./extensions/IERC20Metadata.sol";
import "../../utils/Context.sol";

/**
 * @dev Implementation of the {IERC20} interface.
 *
 * This implementation is agnostic to the way tokens are created. This means
 * that a supply mechanism has to be added in a derived contract using {_mint}.
 * For a generic mechanism see {ERC20PresetMinterPauser}.
 *
 * TIP: For a detailed writeup see our guide
 * https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * We have followed general OpenZeppelin Contracts guidelines: functions revert
 * instead returning `false` on failure. This behavior is nonetheless
 * conventional and does not conflict with the expectations of ERC20
 * applications.
 *
 * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
 * This allows applications to reconstruct the allowance for all accounts just
 * by listening to said events. Other implementations of the EIP may not emit
 * these events, as it isn't required by the specification.
 *
 * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
 * functions have been added to mitigate the well-known issues around setting
 * allowances. See {IERC20-approve}.
 */
contract ERC20 is Context, IERC20, IERC20Metadata {
    mapping(address => uint256) private _balances;

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

    uint256 private _totalSupply;

    string private _name;
    string private _symbol;

    /**
     * @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_) {
        _name = name_;
        _symbol = symbol_;
    }

    /**
     * @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 18;
    }

    /**
     * @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:
     *
     * - `to` cannot be the zero address.
     * - the caller must have a balance of at least `amount`.
     */
    function transfer(address to, uint256 amount) public virtual override returns (bool) {
        address owner = _msgSender();
        _transfer(owner, to, 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}.
     *
     * NOTE: If `amount` is the maximum `uint256`, the allowance is not updated on
     * `transferFrom`. This is semantically equivalent to an infinite approval.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) public virtual override returns (bool) {
        address owner = _msgSender();
        _approve(owner, 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}.
     *
     * NOTE: Does not update the allowance if the current allowance
     * is the maximum `uint256`.
     *
     * Requirements:
     *
     * - `from` and `to` cannot be the zero address.
     * - `from` must have a balance of at least `amount`.
     * - the caller must have allowance for ``from``'s tokens of at least
     * `amount`.
     */
    function transferFrom(
        address from,
        address to,
        uint256 amount
    ) public virtual override returns (bool) {
        address spender = _msgSender();
        _spendAllowance(from, spender, amount);
        _transfer(from, to, amount);
        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) {
        address owner = _msgSender();
        _approve(owner, spender, allowance(owner, spender) + 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) {
        address owner = _msgSender();
        uint256 currentAllowance = allowance(owner, spender);
        require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
        unchecked {
            _approve(owner, spender, currentAllowance - subtractedValue);
        }

        return true;
    }

    /**
     * @dev Moves `amount` of tokens from `from` to `to`.
     *
     * This 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:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `from` must have a balance of at least `amount`.
     */
    function _transfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {
        require(from != address(0), "ERC20: transfer from the zero address");
        require(to != address(0), "ERC20: transfer to the zero address");

        _beforeTokenTransfer(from, to, amount);

        uint256 fromBalance = _balances[from];
        require(fromBalance >= amount, "ERC20: transfer amount exceeds balance");
        unchecked {
            _balances[from] = fromBalance - amount;
        }
        _balances[to] += amount;

        emit Transfer(from, to, amount);

        _afterTokenTransfer(from, to, 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 _mint(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: mint to the zero address");

        _beforeTokenTransfer(address(0), account, amount);

        _totalSupply += amount;
        _balances[account] += amount;
        emit Transfer(address(0), account, amount);

        _afterTokenTransfer(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);

        uint256 accountBalance = _balances[account];
        require(accountBalance >= amount, "ERC20: burn amount exceeds balance");
        unchecked {
            _balances[account] = accountBalance - amount;
        }
        _totalSupply -= amount;

        emit Transfer(account, address(0), amount);

        _afterTokenTransfer(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);
    }

    /**
     * @dev Updates `owner` s allowance for `spender` based on spent `amount`.
     *
     * Does not update the allowance amount in case of infinite allowance.
     * Revert if not enough allowance is available.
     *
     * Might emit an {Approval} event.
     */
    function _spendAllowance(
        address owner,
        address spender,
        uint256 amount
    ) internal virtual {
        uint256 currentAllowance = allowance(owner, spender);
        if (currentAllowance != type(uint256).max) {
            require(currentAllowance >= amount, "ERC20: insufficient allowance");
            unchecked {
                _approve(owner, spender, currentAllowance - amount);
            }
        }
    }

    /**
     * @dev Hook that is called before any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * will be transferred to `to`.
     * - when `from` is zero, `amount` tokens will be minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens will be burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {}

    /**
     * @dev Hook that is called after any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * has been transferred to `to`.
     * - when `from` is zero, `amount` tokens have been minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens have been burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _afterTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {}
}

// File: @openzeppelin/contracts/utils/math/SafeMath.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;
        }
    }
}

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



// 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;
    }
}

// File: @openzeppelin/contracts/token/ERC20/extensions/IERC20Metadata.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/IERC20Metadata.sol)

pragma solidity ^0.8.0;

import "../IERC20.sol";

/**
 * @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);
}