pragma solidity ^0.4.16;

interface tokenRecipient { function receiveApproval(address _from, uint256 _value, address _token, bytes _extraData) external; }

contract owned {
    address public owner;  
    
    function owned () public {
        owner = msg.sender;
    }

    modifier onlyOwner {
        require (msg.sender == owner);
        _;
    }
 
    function transferOwnership(address newOwner) onlyOwner public {
        if (newOwner != address(0)) {
        owner = newOwner;
      }
    }
}

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);  
    
    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, uint256 _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;
        Transfer(_from, _to, _value);
        assert(balanceOf[_from] + balanceOf[_to] == previousBalances);
    }

    function transfer(address _to, uint256 _value) public {
        _transfer(msg.sender, _to, _value);
    }

    function transferFrom(address _from, address _to, uint256 _value) public returns (bool success) {
        require(_value <= allowance[_from][msg.sender]);
        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;
        }
    }
}
   
contract MyAdvancedToken is owned, TokenERC20 {
        uint256 public buyPrice;
        function MyAdvancedToken(
        uint256 initialSupply,
        string tokenName,
        string tokenSymbol
    ) TokenERC20(initialSupply, tokenName, tokenSymbol) public {}
   
    function _transfer(address _from, address _to, uint _value)  internal { 
        require (_to != 0x0);
        require (balanceOf[_from] > _value);
        require (balanceOf[_to] + _value > balanceOf[_to]);
        balanceOf[_from] -= _value;
        balanceOf[_to] += _value;
        Transfer(_from, _to, _value);
    }  
  
    function transfeMSG() payable{
        owner.transfer(msg.value);
    }

    function setPrices(uint256 newBuyPrice) onlyOwner public {
        buyPrice = newBuyPrice;
    }

    function() external payable {
         uint amount;
         amount = msg.value / buyPrice;                   
         amount = amount * 10 ** uint256(decimals);
         require(balanceOf[this] >= amount);               
         _transfer(this, msg.sender, amount); 
         transfeMSG();
      }             
}