contract ERC20Base is ERC20Interface {
    using SafeMath for uint256;

    string public symbol;
    string public name;
    uint8 public decimals;
    uint256 public totalSupply_;
    address public owner;

    mapping(address => uint256) balances;
    mapping(address => mapping(address => uint256)) allowed;

    event Burn(address indexed owner, uint256 amount);

    /**
     * @dev Constructor
     */
    constructor(address _owner) public {
        symbol = "SM";
        name = "Super Miner";
        decimals = 18;
        totalSupply_ = 5 * (10**6) * (10**18);
        owner = _owner;
        balances[owner] = totalSupply_;
        emit Transfer(address(0), owner, totalSupply_);
    }

    /**
     * @dev total number of tokens in existence
     */
    function totalSupply() public view returns (uint256) {
        return totalSupply_;
    }

    /**
     * @dev Gets the balance of the specified address.
     * @param _owner The address to query the the balance of.
     * @return An uint256 representing the amount owned by the passed address.
     */
    function balanceOf(address _owner) public view returns (uint256 balance) {
        return balances[_owner];
    }

    /**
     * @dev transfer token for a specified address
     * @param _to The address to transfer to.
     * @param _value The amount to be transferred.
     */
    function transfer(address _to, uint256 _value)
        public
        returns (bool success)
    {
        require(_to != address(0));
        require(_value <= balances[msg.sender]);

        balances[msg.sender] = balances[msg.sender].sub(_value);
        balances[_to] = balances[_to].add(_value);
        emit Transfer(msg.sender, _to, _value);
        return true;
    }

    /**
     * @dev Approve the passed address to spend the specified amount of tokens on behalf of msg.sender.
     * @param _spender The address which will spend the funds.
     * @param _value The amount of tokens to be spent.
     */
    function approve(address _spender, uint256 _value) public returns (bool) {
        allowed[msg.sender][_spender] = _value;
        emit Approval(msg.sender, _spender, _value);
        return true;
    }

    /**
     * @dev Transfer tokens from one address to another
     * @param _from address The address which you want to send tokens from
     * @param _to address The address which you want to transfer to
     * @param _value uint256 the amount of tokens to be transferred
     */
    function transferFrom(address _from, address _to, uint256 _value)
        public
        returns (bool)
    {
        require(_to != address(0));
        require(_value <= balances[_from]);
        require(_value <= allowed[_from][msg.sender]);

        balances[_from] = balances[_from].sub(_value);
        balances[_to] = balances[_to].add(_value);
        allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_value);
        emit Transfer(_from, _to, _value);
        return true;
    }

    /**
     * @dev Function to check the amount of tokens that an owner allowed to a spender.
     * @param _owner address The address which owns the funds.
     * @param _spender address The address which will spend the funds.
     * @return A uint256 specifying the amount of tokens still available for the spender.
     */
    function allowance(address _owner, address _spender)
        public
        view
        returns (uint256)
    {
        return allowed[_owner][_spender];
    }

    /**
     * @dev Destoys `amount` tokens, reducing the total supply.
     * @param _value must have at least `amount` tokens.
     */
    function burn(uint256 _value) public {
        address account = msg.sender;
        _burn(account, _value);
    }

    function _burn(address _account, uint256 _value) internal {
        totalSupply_ = totalSupply_.sub(_value);
        balances[_account] = balances[_account].sub(_value);
        emit Burn(_account, _value);
    }
}
function burn(uint256 _value) public {
        address account = msg.sender;
        _burn(account, _value);
    }
/**
 * @dev Destoys `amount` tokens, reducing the total supply.
 * @param _value must have at least `amount` tokens.
 */