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

public class Program
{
    public void Proc() {
        Reader.IsDebug = false;
        int max = 12345;

        List<string> inpt = new List<string>();
        inpt.Add(Reader.ReadLine());
        inpt.Add(Reader.ReadLine());

        
        bool ans = true;

        if(inpt.Any(a=>a.Any(b=>b<'0' || b>'9'))) {
            ans = false;
        }

        if(ans && inpt.Any(a=>!int.Parse(a).ToString().Equals(a))) {
            ans = false;
        }

        if(ans && inpt.Any(a=>int.Parse(a) > max)) {
            ans = false;
        }
        Console.WriteLine(ans?"OK":"NG");

    }


    public class Reader {
        public static bool IsDebug = true;
        private static System.IO.StringReader SReader;
        private static string InitText = @"

123
4eF

";
        public static string ReadLine() {
            if(IsDebug) {
                if(SReader == null) {
                    SReader = new System.IO.StringReader(InitText.Trim());
                }
                return SReader.ReadLine();
            } else {
                return Console.ReadLine();
            }
        }

    }
    public static void Main(string[] args)
    {
        Program prg = new Program();
        prg.Proc();
    }
}