static void Main(string[] args)
        {
            int compGuess = 0;

            System.Console.WriteLine("welcome to MasterMind,playing with 4 colors:R,G,B,Y.");
            System.Console.WriteLine("please choose your secret combination and then press enter.");
            System.Console.ReadLine();
            System.Console.WriteLine("after each guess of the compter, enter the hint as a string of B and W.");
            MasterMindPlayer.Player player = new MasterMindPlayer.Player(100, 4);
            string res = player.Play();

            ++compGuess;
            System.Console.WriteLine("compter guess {0}: {1}", compGuess, res);
            string userAnser = System.Console.ReadLine();

            while (userAnser != "V")
            {
                MasterMindPlayer.Hint hint = new MasterMindPlayer.Hint();
                hint.black = 0;
                hint.white = 0;
                foreach (var peg in userAnser)
                {
                    if (peg == 'B')
                    {
                        ++hint.black;
                    }
                    if (peg == 'W')
                    {
                        ++hint.white;
                    }
                }
                res = player.Play(hint);
                ++compGuess;
                System.Console.WriteLine("computer guess {0}: {1}", compGuess, res);
                userAnser = System.Console.ReadLine();
            }
        }
        static void Test()
        {
            MasterMindPlayer.Player p = new MasterMindPlayer.Player(100, 4);
            string secret             = p.GetRndComb();
            int    moves = 0;

            try
            {
                string guess = p.Play();
                ++moves;
                var hint = p.hint(guess, secret);
                while (hint.black < 4)
                {
                    guess = p.Play(hint);
                    ++moves;
                    hint = p.hint(guess, secret);
                }
                System.Console.WriteLine("secret:{0},computer guess after {1}", secret, moves);
            }
            catch (Exception)
            {
                System.Console.WriteLine("secret:{0},computer fail", secret);
            }
        }