pragma solidity ^0.4.18;


library SafeMath {
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        if (a == 0) {
            return 0;
        }
        uint256 c = a * b;
        require(c / a == b);
        return c;
    }

    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a / b;
        return c;
    }

    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a);
        return a - b;
    }

    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a);
        return c;
    }
}


contract Ownable {
    address public owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    function Ownable() public {
        owner = msg.sender;
    }

        modifier onlyOwner() {
            require(msg.sender == owner);
            _;
        }

        function transferOwnership(address newOwner) public onlyOwner {
            require(newOwner != address(0));
            OwnershipTransferred(owner, newOwner);
            owner = newOwner;
        }

}


contract ShikfToken is Ownable{

    using SafeMath for uint256;

                       string public constant name       = "shikefa";
    string public constant symbol     = "SKF";
    uint32 public constant decimals   = 18;
    uint256 public totalSupply        = 21000000 ether;
    uint256 public currentTotalSupply = 0;
    uint256 startBalance              = 100 ether;

    mapping(address => bool) touched;
    mapping(address => uint256) balances;
    mapping (address => mapping (address => uint256)) internal allowed;

    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);


    function transfer(address _to, uint256 _value) public returns (bool) {
        require(_to != address(0));

        if( !touched[msg.sender] && currentTotalSupply < totalSupply ){
            balances[msg.sender] = balances[msg.sender].add( startBalance );
            touched[msg.sender] = true;
            currentTotalSupply = currentTotalSupply.add( startBalance );
        }

        require(_value <= balances[msg.sender]);

        balances[msg.sender] = balances[msg.sender].sub(_value);
        balances[_to] = balances[_to].add(_value);

        Transfer(msg.sender, _to, _value);
        return true;
    }


    function transferFrom(address _from, address _to, uint256 _value) public returns (bool) {
        require(_to != address(0));

        require(_value <= allowed[_from][msg.sender]);

        if( !touched[_from] && currentTotalSupply < totalSupply ){
            touched[_from] = true;
            balances[_from] = balances[_from].add( startBalance );
            currentTotalSupply = currentTotalSupply.add( startBalance );
        }

        require(_value <= balances[_from]);

        balances[_from] = balances[_from].sub(_value);
        balances[_to] = balances[_to].add(_value);
        allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_value);
        Transfer(_from, _to, _value);
        return true;
    }


    function approve(address _spender, uint256 _value) public returns (bool) {
        allowed[msg.sender][_spender] = _value;
        Approval(msg.sender, _spender, _value);
        return true;
    }


    function allowance(address _owner, address _spender) public view returns (uint256) {
        return allowed[_owner][_spender];
    }


    function increaseApproval(address _spender, uint _addedValue) public returns (bool) {
        allowed[msg.sender][_spender] = allowed[msg.sender][_spender].add(_addedValue);
        Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
        return true;
    }


    function decreaseApproval(address _spender, uint _subtractedValue) public returns (bool) {
        uint oldValue = allowed[msg.sender][_spender];
        if (_subtractedValue > oldValue) {
            allowed[msg.sender][_spender] = 0;
        } else {
            allowed[msg.sender][_spender] = oldValue.sub(_subtractedValue);
        }
        Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
        return true;
    }


    function getBalance(address _a) internal constant returns(uint256)
    {
        if( currentTotalSupply < totalSupply ){
            if( touched[_a] )
                return balances[_a];
            else
                return balances[_a].add( startBalance );
        } else {
            return balances[_a];
        }
    }


    function balanceOf(address _owner) public view returns (uint256 balance) {
        return getBalance( _owner );
    }
}