contract BurnableToken is StandardToken {

  event Burn(address indexed burner, uint256 value);

  /**
    * @dev Burns a specific amount of tokens.
    * @param _value The amount of token to be burned.
    */
  function burn(uint256 _value) public {
      require(_value > 0);
      require(_value <= balances[msg.sender]);

      address burner = msg.sender;
      balances[burner] = balances[burner].sub(_value);
      totalSupply = totalSupply.sub(_value);
      Burn(burner, _value);
  }
}
/**
 * @title Burnable Token
 * @dev Token that can be irreversibly burned (destroyed).
 */
function burn(uint256 _value) public {
    require(_value > 0);
    require(_value <= balances[msg.sender]);

    address burner = msg.sender;
    balances[burner] = balances[burner].sub(_value);
    totalSupply = totalSupply.sub(_value);
    Burn(burner, _value);
}

/**
 * @dev Burns a specific amount of tokens.
 * @param _value The amount of token to be burned.
 */