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

public class Magatro
{
    static string A, B;
    static void Main()
    {
        string abc = "qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM";
        A = Console.ReadLine();
        B = Console.ReadLine();
        for(int i = 0; i < 26 * 2; i++)
        {
            if (A.IndexOf(abc[i]) >= 0|| B.IndexOf(abc[i]) >= 0)
            {
                Console.WriteLine("NG");
                return;
            }
        }
        if ((A[0] == '0'&&A!="0") || (B[0] == '0' && B != "0"))
        {
            Console.WriteLine("NG");
            return;
        }
        if (int.Parse(A) > 12345 || int.Parse(B) > 12345)
        {
            Console.WriteLine("NG");
            return;
        }
        Console.WriteLine("OK");
    }
  
}