using System;

namespace B
{
    class Program
    {
        static void Main(string[] args)
        {
            var A = Console.ReadLine();
            var B = Console.ReadLine();

            var result = IsValid(A) && IsValid(B)
                ? "OK" : "NG";

            Console.Write(result);
        }

        static bool IsValid(string value)
        {
            for (var i = 0; i < value.Length; i++)
            {
                var v = value[i];
                if (!IsNumber(v)) return false;
                if (i == 0 && v == '0' && value.Length != 1) return false;
            }

            if (int.Parse(value) > 12345) return false;

            return true;
        }

        static bool IsNumber(char value)
        {
            return value == '1'
                || value == '2'
                || value == '3'
                || value == '4'
                || value == '5'
                || value == '6'
                || value == '7'
                || value == '8'
                || value == '9'
                || value == '0';
        }
    }
}