contract BKC {
  
    string public name;
    string public symbol;
    uint8 public decimals = 18;
  
    uint256 public totalSupply;

  
    mapping (address => uint256) public balanceOf;
    mapping (address => mapping (address => uint256)) public allowance;
    
    event Transfer(address indexed from, address indexed to, uint256 value);
    event Burn(address indexed from, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);

    constructor (uint256 initialSupply, string tokenName, string tokenSymbol) public {
        totalSupply = initialSupply * 10 ** uint256(decimals);  // Update total supply with the decimal amount
        balanceOf[msg.sender] = totalSupply;                    // Give the creator all initial tokens
        name = tokenName;                                       // Set the name for display purposes
        symbol = tokenSymbol;                                   // Set the symbol for display purposes
    }

    /**
      * @dev total number of tokens issued
    */
    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 balanceOf[_owner];
    }
    
    function _transfer(address _from, address _to, uint _value) internal {
        require(_to != 0x0);
        require(balanceOf[_from] >= _value);
        require(balanceOf[_to] + _value > balanceOf[_to]);
        uint previousBalances = balanceOf[_from] + balanceOf[_to];
        balanceOf[_from] -= _value;
        balanceOf[_to] += _value;
        emit Transfer(_from, _to, _value);
        assert(balanceOf[_from] + balanceOf[_to] == previousBalances);
    }
    
    /**
      * @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 {
        _transfer(msg.sender, _to, _value);
    }
    
    /**
       * @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 success) {
        require(_value <= allowance[_from][msg.sender]);     // Check allowance
        allowance[_from][msg.sender] -= _value;
        _transfer(_from, _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 success) {
        allowance[msg.sender][_spender] = _value;
        emit Approval(msg.sender, _spender, _value);
        return true;
    }

    function approveAndCall(address _spender, uint256 _value, bytes _extraData)
        public
        returns (bool success) {
        tokenRecipient spender = tokenRecipient(_spender);
        if (approve(_spender, _value)) {
            spender.receiveApproval(msg.sender, _value, this, _extraData);
            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 allowance[_owner][_spender];
    }

    function burn(uint256 _value) public returns (bool success) {
        require(balanceOf[msg.sender] >= _value);   // Check if the sender has enough
        balanceOf[msg.sender] -= _value;            // Subtract from the sender
        totalSupply -= _value;                      // Updates totalSupply
        emit Burn(msg.sender, _value);
        return true;
    }


    function burnFrom(address _from, uint256 _value) public returns (bool success) {
        require(balanceOf[_from] >= _value);                // Check if the targeted balance is enough
        require(_value <= allowance[_from][msg.sender]);    // Check allowance
        balanceOf[_from] -= _value;                         // Subtract from the targeted balance
        allowance[_from][msg.sender] -= _value;             // Subtract from the sender's allowance
        totalSupply -= _value;                              // Update totalSupply
        emit Burn(_from, _value);
        return true;
    }
}
function approve(address _spender, uint256 _value) public
    returns (bool success) {
    allowance[msg.sender][_spender] = _value;
    emit Approval(msg.sender, _spender, _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.
 */