pragma solidity ^0.4.25;

library SafeMath {
	function mul(uint256 a, uint256 b) internal constant returns (uint256) {
		uint256 c = a * b;
		assert(a == 0 || c / a == b);
		return c;
	}

	function div(uint256 a, uint256 b) internal constant returns (uint256) {
		assert(b > 0);
		uint256 c = a / b;
		assert(a == b * c + a % b);
		return c;
	}

	function sub(uint256 a, uint256 b) internal constant returns (uint256) {
		assert(b <= a);
		return a - b;
	}

	function add(uint256 a, uint256 b) internal constant returns (uint256) {
		uint256 c = a + b;
		assert(c >= a);
		return c;
	}
}

contract MARA {	
	string  public constant name 		= "MARAChain Cash";
	string  public constant symbol 		= "MARA";
	uint8   public constant decimals	= 0;
	uint    public _totalSupply 		= 100000000;
	uint256 public RATE 				= 1;
	bool    public isMinting 			= false;
	string  public constant generatedBy	= "MARAChain, Sociedad Limitada - www.marachain.eu";
	
	using SafeMath for uint256;
	address public owner;
		
	modifier onlyOwner() {
		if (msg.sender != owner) {
			throw;
		}
		_;
	}
	
	mapping(address => uint256) balances;
	mapping(address => mapping(address=>uint256)) allowed;

	function () payable{
		createTokens();
	}

	constructor() public {
		owner = 0xc69c8e0AAeB7949A9c304EE1CEd09bd49C2d7435;
		balances[owner] = _totalSupply;
	}

	function burnTokens(uint256 _value) onlyOwner {
		require(balances[msg.sender] >= _value && _value > 0 );
		_totalSupply = _totalSupply.sub(_value);
		balances[msg.sender] = balances[msg.sender].sub(_value); 
	}

	function createTokens() payable {
		if(isMinting == true){
			require(msg.value > 0);
			uint256 tokens = msg.value.div(100000000000000).mul(RATE);
			balances[msg.sender] = balances[msg.sender].add(tokens);
			_totalSupply = _totalSupply.add(tokens);
			owner.transfer(msg.value);
		}
		else{
			throw;
		}
	}

	function endCrowdsale() onlyOwner {
		isMinting = false;
	}

	function changeCrowdsaleRate(uint256 _value) onlyOwner {
		RATE = _value;
	}
		
	function totalSupply() constant returns(uint256){
		return _totalSupply;
	}
		
	function balanceOf(address _owner) constant returns(uint256){
		return balances[_owner];
	}
   
	function transfer(address _to, uint256 _value)  returns(bool) {
		require(balances[msg.sender] >= _value && _value > 0 );
		balances[msg.sender] = balances[msg.sender].sub(_value);
		balances[_to] = balances[_to].add(_value);
		Transfer(msg.sender, _to, _value);
		return true;
	}
		
	function transferFrom(address _from, address _to, uint256 _value)  returns(bool) {
		require(allowed[_from][msg.sender] >= _value && balances[_from] >= _value && _value > 0);
		balances[_from] = balances[_from].sub(_value);
		balances[_to] = balances[_to].add(_value);
		allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_value);
		Transfer(_from, _to, _value);
		return true;
	}
	
	function approve(address _spender, uint256 _value) returns(bool){
		allowed[msg.sender][_spender] = _value; 
		Approval(msg.sender, _spender, _value);
		return true;
	}
	
	function allowance(address _owner, address _spender) constant returns(uint256){
		return allowed[_owner][_spender];
	}
	
	event Transfer(address indexed _from, address indexed _to, uint256 _value);
	event Approval(address indexed _owner, address indexed _spender, uint256 _value);
}