Contract Source Code:

pragma solidity ^0.4.11;


library SafeMath {

  function mul(uint256 a, uint256 b) internal pure returns (uint256) {
    if (a == 0) {
      return 0;
    }
    uint256 c = a * b;
    assert(c / a == b);
    return c;
  }

  function div(uint256 a, uint256 b) internal pure returns (uint256) {
    // assert(b > 0); // Solidity automatically throws when dividing by 0
    uint256 c = a / b;
    // assert(a == b * c + a % b); // There is no case in which this doesn't hold
    return c;
  }

  function sub(uint256 a, uint256 b) internal pure returns (uint256) {
    assert(b <= a);
    return a - b;
  }

  function add(uint256 a, uint256 b) internal pure returns (uint256) {
    uint256 c = a + b;
    assert(c >= a);
    return c;
  }
}

interface IERC20{
    function totalSupply() constant returns (uint256 totalSupply);
    function balanceOf(address _owner) constant returns (uint256 balance);
    function transfer(address _to, uint256 _value) returns (bool success);
    function transferFrom(address _from, address _to, uint256 _value) returns (bool success);
    function approve(address _spender, uint256 _value) returns (bool success);
    function allowance(address _owner, address _spender) constant returns (uint256 remaining);
    event Transfer(address indexed _from, address indexed _to, uint256 _value);
    event Approval(address indexed _owner, address indexed _spender, uint256 _value);
}


contract DateTime {
        /*
         *  Date and Time utilities for ethereum contracts
         *
         */
        struct _DateTime {
                uint16 year;
                uint8 month;
                uint8 day;
                uint8 hour;
                uint8 minute;
                uint8 second;
                uint8 weekday;
        }

        uint constant DAY_IN_SECONDS = 86400;
        uint constant YEAR_IN_SECONDS = 31536000;
        uint constant LEAP_YEAR_IN_SECONDS = 31622400;

        uint constant HOUR_IN_SECONDS = 3600;
        uint constant MINUTE_IN_SECONDS = 60;

        uint16 constant ORIGIN_YEAR = 1970;

        function isLeapYear(uint16 year) public pure returns (bool) {
                if (year % 4 != 0) {
                        return false;
                }
                if (year % 100 != 0) {
                        return true;
                }
                if (year % 400 != 0) {
                        return false;
                }
                return true;
        }

        function leapYearsBefore(uint year) public pure returns (uint) {
                year -= 1;
                return year / 4 - year / 100 + year / 400;
        }

        function getDaysInMonth(uint8 month, uint16 year) public pure returns (uint8) {
                if (month == 1 || month == 3 || month == 5 || month == 7 || month == 8 || month == 10 || month == 12) {
                        return 31;
                }
                else if (month == 4 || month == 6 || month == 9 || month == 11) {
                        return 30;
                }
                else if (isLeapYear(year)) {
                        return 29;
                }
                else {
                        return 28;
                }
        }

        function parseTimestamp(uint timestamp) internal pure returns (_DateTime dt) {
                uint secondsAccountedFor = 0;
                uint buf;
                uint8 i;

                // Year
                dt.year = getYear(timestamp);
                buf = leapYearsBefore(dt.year) - leapYearsBefore(ORIGIN_YEAR);

                secondsAccountedFor += LEAP_YEAR_IN_SECONDS * buf;
                secondsAccountedFor += YEAR_IN_SECONDS * (dt.year - ORIGIN_YEAR - buf);

                // Month
                uint secondsInMonth;
                for (i = 1; i <= 12; i++) {
                        secondsInMonth = DAY_IN_SECONDS * getDaysInMonth(i, dt.year);
                        if (secondsInMonth + secondsAccountedFor > timestamp) {
                                dt.month = i;
                                break;
                        }
                        secondsAccountedFor += secondsInMonth;
                }

                // Day
                for (i = 1; i <= getDaysInMonth(dt.month, dt.year); i++) {
                        if (DAY_IN_SECONDS + secondsAccountedFor > timestamp) {
                                dt.day = i;
                                break;
                        }
                        secondsAccountedFor += DAY_IN_SECONDS;
                }

                // Hour
                dt.hour = getHour(timestamp);

                // Minute
                dt.minute = getMinute(timestamp);

                // Second
                dt.second = getSecond(timestamp);

                // Day of week.
                dt.weekday = getWeekday(timestamp);
        }

        function getYear(uint timestamp) public pure returns (uint16) {
                uint secondsAccountedFor = 0;
                uint16 year;
                uint numLeapYears;

                // Year
                year = uint16(ORIGIN_YEAR + timestamp / YEAR_IN_SECONDS);
                numLeapYears = leapYearsBefore(year) - leapYearsBefore(ORIGIN_YEAR);

                secondsAccountedFor += LEAP_YEAR_IN_SECONDS * numLeapYears;
                secondsAccountedFor += YEAR_IN_SECONDS * (year - ORIGIN_YEAR - numLeapYears);

                while (secondsAccountedFor > timestamp) {
                        if (isLeapYear(uint16(year - 1))) {
                                secondsAccountedFor -= LEAP_YEAR_IN_SECONDS;
                        }
                        else {
                                secondsAccountedFor -= YEAR_IN_SECONDS;
                        }
                        year -= 1;
                }
                return year;
        }

        function getMonth(uint timestamp) public pure returns (uint8) {
                return parseTimestamp(timestamp).month;
        }

        function getDay(uint timestamp) public pure returns (uint8) {
                return parseTimestamp(timestamp).day;
        }

        function getHour(uint timestamp) public pure returns (uint8) {
                return uint8((timestamp / 60 / 60) % 24);
        }

        function getMinute(uint timestamp) public pure returns (uint8) {
                return uint8((timestamp / 60) % 60);
        }

        function getSecond(uint timestamp) public pure returns (uint8) {
                return uint8(timestamp % 60);
        }

        function getWeekday(uint timestamp) public pure returns (uint8) {
                return uint8((timestamp / DAY_IN_SECONDS + 4) % 7);
        }

        function toTimestamp(uint16 year, uint8 month, uint8 day) public pure returns (uint timestamp) {
                return toTimestamp(year, month, day, 0, 0, 0);
        }

        function toTimestamp(uint16 year, uint8 month, uint8 day, uint8 hour) public pure returns (uint timestamp) {
                return toTimestamp(year, month, day, hour, 0, 0);
        }

        function toTimestamp(uint16 year, uint8 month, uint8 day, uint8 hour, uint8 minute) public pure returns (uint timestamp) {
                return toTimestamp(year, month, day, hour, minute, 0);
        }

        function toTimestamp(uint16 year, uint8 month, uint8 day, uint8 hour, uint8 minute, uint8 second) public pure returns (uint timestamp) {
                uint16 i;

                // Year
                for (i = ORIGIN_YEAR; i < year; i++) {
                        if (isLeapYear(i)) {
                                timestamp += LEAP_YEAR_IN_SECONDS;
                        }
                        else {
                                timestamp += YEAR_IN_SECONDS;
                        }
                }

                // Month
                uint8[12] memory monthDayCounts;
                monthDayCounts[0] = 31;
                if (isLeapYear(year)) {
                        monthDayCounts[1] = 29;
                }
                else {
                        monthDayCounts[1] = 28;
                }
                monthDayCounts[2] = 31;
                monthDayCounts[3] = 30;
                monthDayCounts[4] = 31;
                monthDayCounts[5] = 30;
                monthDayCounts[6] = 31;
                monthDayCounts[7] = 31;
                monthDayCounts[8] = 30;
                monthDayCounts[9] = 31;
                monthDayCounts[10] = 30;
                monthDayCounts[11] = 31;

                for (i = 1; i < month; i++) {
                        timestamp += DAY_IN_SECONDS * monthDayCounts[i - 1];
                }

                // Day
                timestamp += DAY_IN_SECONDS * (day - 1);

                // Hour
                timestamp += HOUR_IN_SECONDS * (hour);

                // Minute
                timestamp += MINUTE_IN_SECONDS * (minute);

                // Second
                timestamp += second;

                return timestamp;
        }
}

contract ySignToken is IERC20{
    
    using SafeMath for uint256;
    uint constant MINUTE_IN_SECONDS = 60;
    uint constant HOUR_IN_SECONDS = 3600;
    uint constant DAY_IN_SECONDS = 86400;
    
    uint public  _totalSupply = 18400000000000000000000000;
    uint public constant Max = 80000000000000000000000000;
    
    uint256 public startTime ;
    
    string public constant symbol = "YSN";
    string public constant name = "ySignToken";
    uint8 public constant decimals = 18; 
   
    uint256 public  RATE;
    uint256 public  Check = 0;
    
    address public owner;
    
    mapping(address => uint256) balances;
    mapping(address => mapping(address => uint256)) allowed;
    
    function() payable{
        createToken();
    }
    
    
    function ySignToken(){
       balances[msg.sender] = _totalSupply;
       owner = msg.sender;
       startTime = now;
    }
    
    function createToken() payable{
       uint256 tokenss = msg.value;
         if(now < startTime + (7 * DAY_IN_SECONDS + 6 * HOUR_IN_SECONDS)){
           RATE = 5556;
           if(_totalSupply <= 28400000000000000000000000){
               Check = 1;
           }
       }
	   else  if(now < startTime + (14 * DAY_IN_SECONDS)){
           RATE = 2778;
           if(_totalSupply <= 38400000000000000000000000){
               Check = 1;
           }
       }
	   else  if(now < startTime + (21 * DAY_IN_SECONDS)){
           RATE = 1852;
           if(_totalSupply <= 48400000000000000000000000){
               Check = 1;
           }
       }
	   else  if(now < startTime + (28 * DAY_IN_SECONDS)){
           RATE = 1389;
            if(_totalSupply <= 58400000000000000000000000){
               Check = 1;
           }
       }
       else RATE = 1191; 
        require(
        msg.value > 0    
        && _totalSupply.add(msg.value.mul(RATE)) <= Max
        && Check > 0
        );
        
        uint256 tokens = msg.value.mul(RATE);
        balances[msg.sender] = balances[msg.sender].add(tokens);
        _totalSupply = _totalSupply.add(tokens);
        owner.transfer(msg.value);
        Check = 0;
    }
    
     function totalSupply() constant returns (uint256 totalSupply){
        return _totalSupply;
     }
     
    function balanceOf(address _owner) constant returns (uint256 balance){
        return balances[_owner];
    }
    
    function transfer(address _to, uint256 _value) returns (bool success){
        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 success){
        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 success){
        allowed[msg.sender][_spender] = _value;   
        Approval(msg.sender,_spender,_value);
        return true;
    }
    
    function allowance(address _owner, address _spender) constant returns (uint256 remaining){
        return allowed[_owner][_spender];
    }
    
    event Transfer(address indexed _from, address indexed _to, uint256 _value);
    event Approval(address indexed _owner, address indexed _spender, uint256 _value);
    
       
}