pragma solidity ^0.4.18;

/*
  Realty Coin
  Worldwide real estate coin
  2017
*/

library SafeMath {
  function mul(uint a, uint b) internal returns (uint) {
    uint c = a * b;
    assert(a == 0 || c / a == b);
    return c;
  }
  function div(uint a, uint b) internal returns (uint) {
    assert(b > 0);
    uint c = a / b;
    assert(a == b * c + a % b);
    return c;
  }
  function sub(uint a, uint b) internal returns (uint) {
    assert(b <= a);
    return a - b;
  }
  function add(uint a, uint b) internal returns (uint) {
    uint c = a + b;
    assert(c >= a);
    return c;
  }
  function max64(uint64 a, uint64 b) internal constant returns (uint64) {
    return a >= b ? a : b;
  }
  function min64(uint64 a, uint64 b) internal constant returns (uint64) {
    return a < b ? a : b;
  }
  function max256(uint256 a, uint256 b) internal constant returns (uint256) {
    return a >= b ? a : b;
  }
  function min256(uint256 a, uint256 b) internal constant returns (uint256) {
    return a < b ? a : b;
  }
  function assert(bool assertion) internal {
    if (!assertion) {
      throw;
    }
  }
}

contract ERC20Basic {
  uint public totalSupply;
  function balanceOf(address who) constant returns (uint);
  function transfer(address to, uint value);
  event Transfer(address indexed from, address indexed to, uint value);
}
contract ERC20 is ERC20Basic {
  function allowance(address owner, address spender) constant returns (uint);
  function transferFrom(address from, address to, uint value);
  function approve(address spender, uint value);
  event Approval(address indexed owner, address indexed spender, uint value);
}

contract newToken is ERC20Basic {
  
  using SafeMath for uint;
  
  mapping(address => uint) balances;
  

  modifier onlyPayloadSize(uint size) {
     if(msg.data.length < size + 4) {
       throw;
     }
     _;
  }
  function transfer(address _to, uint _value) onlyPayloadSize(2 * 32) {
    balances[msg.sender] = balances[msg.sender].sub(_value);
    balances[_to] = balances[_to].add(_value);
    Transfer(msg.sender, _to, _value);
  }
  function balanceOf(address _owner) constant returns (uint balance) {
    return balances[_owner];
  }
}

contract RTC is newToken, ERC20 {
  mapping (address => mapping (address => uint)) allowed;
  function transferFrom(address _from, address _to, uint _value) onlyPayloadSize(3 * 32) {
    var _allowance = allowed[_from][msg.sender];
    // Check is not needed because sub(_allowance, _value) will already throw if this condition is not met
    // if (_value > _allowance) throw;
    balances[_to] = balances[_to].add(_value);
    balances[_from] = balances[_from].sub(_value);
    allowed[_from][msg.sender] = _allowance.sub(_value);
    Transfer(_from, _to, _value);
  }
  function approve(address _spender, uint _value) {
    // To change the approve amount you first have to reduce the addresses`
    //  allowance to zero by calling approve(_spender, 0) if it is not
    //  already 0 to mitigate the race condition described here:
    if ((_value != 0) && (allowed[msg.sender][_spender] != 0)) throw;
    allowed[msg.sender][_spender] = _value;
    Approval(msg.sender, _spender, _value);
  }
  function allowance(address _owner, address _spender) constant returns (uint remaining) {
    return allowed[_owner][_spender];
  }
}

contract RealtyCoin is RTC {
  string public constant name = "RealtyCoin";
  string public constant symbol = "RTC";
  uint public constant decimals = 4;
  uint256 public initialSupply;
    
  function RealtyCoin () { 
     totalSupply = 500000000 * 10 ** decimals;
      balances[msg.sender] = totalSupply;
      initialSupply = totalSupply; 
        Transfer(0, this, totalSupply);
        Transfer(this, msg.sender, totalSupply);
  }
}