pragma solidity ^0.4.18;

contract owned {
    address public owner;

    function owned() public {
        owner = msg.sender;
    }

    modifier onlyOwner {
        require(msg.sender == owner);
        _;
    }

    function transferOwnership(address newOwner) onlyOwner public {
        owner = newOwner;
    }
}

contract EduCoin is owned {
    string public constant name = "EduCoin";
    string public constant symbol = "EDU";
    uint256 private constant _INITIAL_SUPPLY = 15000000000;  //初始数字货币量150亿
    uint8 public decimals = 0;

    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 EduCoin (
        address genesis
    ) public {
        owner = msg.sender;
        require(owner != 0x0);
        require(genesis != 0x0);
        totalSupply = _INITIAL_SUPPLY;
        balanceOf[genesis] = totalSupply;
    }

    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;
        Transfer(_from, _to, _value);
        assert(balanceOf[_from] + balanceOf[_to] == previousBalances);
    }

    function transfer(address _to, uint256 _value) public {
        _transfer(msg.sender, _to, _value);
    }

}