using System;
using System.Collections.Generic;
using System.Linq;

public class yukicoder
{

    public static bool numberCheck(string s)
    {

        foreach (char c in s)
        {
            if (!char.IsDigit(c))
            {
                return false;
            }
        }

        return true;
    }

    public static bool zeroCheck(string s)
    {

        if (s.Length >= 2)
        {
            if (s.Substring(0, 1) == "0")
            {
                return false;
            }
        }

        return true;
    }

    public static bool rangeCheck(string s)
    {
        int n = int.Parse(s);

        if (n < 0 || n > 12345)
        {
            return false;
        }

        return true;
    }

    public static void Main()
    {
        string a = Console.ReadLine();
        string b = Console.ReadLine();

        bool checkFormat = true;

        if (!numberCheck(a) || !numberCheck(b))
        {
            checkFormat = false;
        }
        else if (!zeroCheck(a) || !zeroCheck(b))
        {
            checkFormat = false;
        }
        else if (!rangeCheck(a) || !rangeCheck(b))
        {
            checkFormat = false;
        }

        if (checkFormat)
        {
            Console.WriteLine("OK");
        }
        else
        {
            Console.WriteLine("NG");
        }
        
    }
}