pragma solidity ^0.4.16;

interface tokenRecipient { function receiveApproval(address _from, uint256 _value, address _token, bytes _extraData) public; }

contract TokenERC20 {
    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);

  
    function TokenERC20(uint256 initialSupply, string tokenName, string tokenSymbol) public {
        totalSupply = initialSupply * 10 ** uint256(decimals); 
        balanceOf[msg.sender] = totalSupply;             
        name = tokenName;                                 
        symbol = tokenSymbol;                              
    }

   
    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];
        // Subtract from the sender
        balanceOf[_from] -= _value;
        // Add the same to the recipient
        balanceOf[_to] += _value;
        Transfer(_from, _to, _value);

        assert(balanceOf[_from] + balanceOf[_to] == previousBalances);
    }

   
    function transfer(address _to, uint256 _value) public  returns (bool) {
        _transfer(msg.sender, _to, _value);
       return true;
    }


    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;
    }

    
    function approve(address _spender, uint256 _value) public
        returns (bool success) {
        allowance[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;
        }
    }

    
    function burn(uint256 _value) public returns (bool success) {
        require(balanceOf[msg.sender] >= _value);   
        balanceOf[msg.sender] -= _value;            
        totalSupply -= _value;                     
        Burn(msg.sender, _value);
        return true;
    }

  
    function burnFrom(address _from, uint256 _value) public returns (bool success) {
        require(balanceOf[_from] >= _value);                
        require(_value <= allowance[_from][msg.sender]);    
        balanceOf[_from] -= _value;                        
        allowance[_from][msg.sender] -= _value;             
        totalSupply -= _value;                             
        Burn(_from, _value);
        return true;
    }
}