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

class Program
{
    static void Main()
    {
        var sc = new Scan();
        string[] a = {sc.Str, sc.Str};
        int lim = 12345;
        
        for (int i = 0; i < 2; i++)
        {
            for (int j = 0; j <= lim; j++)
            {
                if (a[i] == j.ToString()) break;

                if (j == lim)
                {
                    Console.WriteLine("NG");
                    return;
                }
            }
        }
        Console.WriteLine("OK");
    }
}
class Scan
{
    public int Int { get { return int.Parse(Str); } }
    public long Long { get { return long.Parse(Str); } }
    public string Str { get { return Console.ReadLine().Trim(); } }
}