using System;
using System.Linq;

class No446
{
    static void Main()
    {
        var first = Console.ReadLine();
        var IsFirst = first.All(x => char.IsNumber(x)&&x<6) ? (int)Math.Log10(Int32.Parse(first == "0" ? "1" : first)) + 1 == first.Count() : false;
        var second = Console.ReadLine();
        var IsSecond = second.All(x => char.IsNumber(x) && x < 6) ? (int)Math.Log10(Int32.Parse(second == "0" ? "1" : second)) + 1 == second.Count() : false;
        Console.WriteLine(IsFirst && IsSecond ? "OK" : "NG");
    }
}