class Program
    {
        static void Main(string[] args)
        {
            string strA = Console.ReadLine(); 
            string strB = Console.ReadLine();
            int numA = 0;
            int numB = 0;
            bool changeFlg = true;
            if(int.TryParse(strA, out numA) && int.TryParse(strB, out numB))
            {
                if(numA.ToString() != strA || numB.ToString() != strB)
                {
                    changeFlg = false;
                }
            }else {
                changeFlg = false;
            }
            if (changeFlg)
            {
                Console.WriteLine("OK");
            }
            else
            {
                Console.WriteLine("NG");
            }
        }
    }