//Testcase
        static void Main(string[] args)
        {
            Solution sol       = new Solution();
            int      stone_num = new Random().Next(1, 1001);

            if (sol.CanWinNim(stone_num))
            {
                Console.WriteLine("When the number of stones are " + stone_num + ", first win!");
            }
            else
            {
                Console.WriteLine("When the number of stones are " + stone_num + ", second win!");
            }
        }