using System;
using System.Linq;

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