using System;
using System.Linq;

class No446
{
    static void Main()
    {
        var IsTrue = true;
        for (int i = 0; i < 2; ++i)
        {
            var str = Console.ReadLine();
            if (str.All(x => char.IsNumber(x)))
            {
                var firstNum = Int32.Parse(str);
                IsTrue = firstNum <= 12345;
                IsTrue = (int)Math.Log10(firstNum==0?1:firstNum) + 1 == str.Count();
            }
            else IsTrue = false;
            if (!IsTrue) break;
        }
        Console.WriteLine(IsTrue ? "OK" : "NG");
    }
}