static void Main()
        {
            Payment smartTv = new Payment("Sony Bravia", 1500);

            var customer1 = new Customer(
                "Ivan",
                "Angelov",
                "Ivanov",
                8811056253,
                "Sofia, Obelq bl. 125",
                0899963125,
                "*****@*****.**",
                CustomerType.OneTime,
                smartTv);

            var customer2 = customer1.Clone() as Customer;
            customer2.FirstName = "Georgi";
            customer2.MiddleName = "Petrov";
            customer2.LastName = "Georgiev";
            customer2.Id = 9105074815;

            Console.WriteLine(customer1);
            Console.WriteLine(customer2);
            Console.WriteLine(customer1 == customer2);

            var customer3 = new Customer(
                "Dimitar",
                "Rangelov",
                "Dimitrov",
                9204261459,
                "Burgas, Slavejkov bl. 68",
                0888478125,
                "*****@*****.**",
                CustomerType.Diamond,
                new Payment("Vafla Borovetz", 0.25));

            var customer4 = customer3.Clone() as Customer;
            customer4.Id = 7810100663;

            var customers = new List<Customer> { customer1, customer2, customer3, customer4 };

            customers.Sort();
            Console.WriteLine(string.Join("\n", customers));
        }
        private static void Main()
        {
            var forNext = new Payment("Ten", 10);

            var aleks = new Customer(
                "Aleks",
                "Dimitrov",
                7708091215,
                0897588666,
                "*****@*****.**",
                CustomerType.OneTime,
                forNext);

            var dimitar = aleks.Clone() as Customer;
            dimitar.FirstName = "Dimityr";
            dimitar.LastName = "Liroy";

            Console.WriteLine(dimitar);
            Console.WriteLine(aleks);

            var georgi = new Customer(
                "Georgi",
                "Vinin",
                8609085256,
                0898528525,
                "*****@*****.**",
                CustomerType.Diamond);

            var todor = georgi.Clone() as Customer;
            todor.Id = 5606081218;
            todor.LastName = "Ivanov";

            var customers = new List<Customer> { aleks, dimitar, georgi, todor };
            customers.Sort();

            Console.WriteLine("***************************");
            Console.WriteLine(string.Join("\n", customers));
        }