using System;
using System.Linq;

class No446
{
    static void Main()
    {
        var first = Console.ReadLine();
        var IsFirst = first.All(x=>char.IsNumber(x))?Math.Log10(Convert.ToInt32(first)) + 1 == first.Count():false;
        var second = Console.ReadLine();
        var IsSecond = second.All(x => char.IsNumber(x)) ? Math.Log10(Convert.ToInt32(second)) + 1 == second.Count() : false;
        Console.WriteLine(IsFirst && IsSecond ? "OK" : "NG");
    }
}