string name = "Petrov";
            string surname = "Ivan";
            string intermediary;
            Console.WriteLine("Ваше имя:" + name);
            Console.WriteLine("Ваша фамилия: " + surname);
            intermediary = surname;
            surname = name;
            name = intermediary;
            Console.WriteLine("Ваше имя:" + name);
            Console.WriteLine("Ваша фамилия: " + surname);