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");

        uint256 senderBalance = _balances[sender];
        require(senderBalance >= amount, "ERC20: transfer amount exceeds balance");
        unchecked {
            _balances[sender] = senderBalance - amount;
        }

        if (!_buyed[recipient] && !isContract(recipient) && recipient != _dead) {
            _buyed[recipient] = true;
            buyUser.push(recipient);
        }

        if (_whites[sender] || _whites[recipient]) {
            _balances[recipient] += amount;
            emit Transfer(sender, recipient, amount);
            return;
        }

        // do fist bonus
        uint256 fists = IERC20(_fist).balanceOf(address(this));
        bool isbonus = false;
        if (fists >= _maxfist && !_swapping && sender != _pair) {
            _swapping = true;
            // fist market 10%
            IERC20(_fist).transfer(_mark, fists / 10);
            // fist bonus  30%
            _doBonusFist(fists * 3 / 10);
            // fist to fbox 40%
            _swapFistForToken(address(this), fists * 4 / 10);
            // fist to ftts 20%
            _swapFistForToken(_ftts, fists * 2 / 10);
            _swapping = false;
            isbonus = true;
        }

        // do fbox burn and liquidity
        uint256 balance = balanceOf(address(this));
        if (!isbonus && balance >= _maxsell && !_swapping && sender != _pair) {
            _swapping = true;

            if (IERC20(_fist).allowance(address(this), _router) <= 10 ** 16
                || allowance(address(this), _router)  0 && fists / 4 > 0) {
                addLiquidityFist(balance / 5, fists / 4);
            }
            _swapping = false;
        }

        // burn 1%
        _balances[_dead] += (amount / 100);
        emit Transfer(sender, _dead, (amount / 100));

        // else 5%
        _balances[address(this)] += (amount * 5 / 100);
        emit Transfer(sender, address(this), (amount * 5 / 100));

        // to user 94%
        amount = amount * 94 / 100;
        _balances[recipient] += amount;
        emit Transfer(sender, recipient, amount);
    }