public static void OrderSummary(Pizza pizza, Pasta pasta)
        {
            Console.WriteLine("|\n \t\t Your order summary");
            Console.WriteLine("|---------------------------------------------------------------|");
            Console.WriteLine("| Item name \t\t\t Quantity \t Price \t Total  |");
            Console.WriteLine("|---------------------------------------------------------------|");
            if (pizza != null && pasta != null)
            {
                pizza.Display();
                pasta.Display();
                Console.WriteLine("|---------------------------------------------------------------|");
                Console.WriteLine("|\t\t\t\t\t\t Total = {0} AUD |", (pizza.totalAmount + pasta.totalAmount));
            }
            else if (pizza != null)
            {
                pizza.Display();
                Console.WriteLine("|---------------------------------------------------------------|");
                Console.WriteLine("|\t\t\t\t\t\t Total = {0} AUD |", pizza.totalAmount);
            }
            else if (pasta != null)
            {
                pasta.Display();
                Console.WriteLine("|---------------------------------------------------------------|");
                Console.WriteLine("|\t\t\t\t\t\t Total = {0} AUD |", pasta.totalAmount);
            }

            Console.WriteLine("|---------------------------------------------------------------|\n");
            Console.WriteLine("| \t\t Offer");
            Console.WriteLine("|---------------------------------------------------------------|");
            if (pizza != null && pizza.countOrder >= 3 && pasta != null && pasta.countOrder >= 3)
            {
                pizza.DisplayOffer();
                pasta.DisplayOffer();
                Console.WriteLine("|A small box of Baklava (a famous dessert item)");
            }
            else if (pizza != null && pizza.countOrder >= 3)
            {
                pizza.DisplayOffer();
            }
            else if (pasta != null && pasta.countOrder >= 3)
            {
                pasta.DisplayOffer();
            }
            else
            {
                Console.WriteLine("| \t\t No offer received");
            }
            Console.WriteLine("|---------------------------------------------------------------|\n\n");
        }
        static void Main(string[] args)
        {
            Pizza  pizza = null;
            Pasta  pasta = null;
            string oprInput;

            do
            {
                // Display menu.
                HeaderInfo();
                Console.Write("Input Operation: ");
                oprInput = Console.ReadLine();  // Taking input operation from the console.
                switch (oprInput)
                {
                case "0":     // to exit the program
                    Environment.Exit(0);
                    break;

                case "1":     // Pizza operations.
                    Console.Clear();
                    pizza = new Pizza();
                    pizza.InitLoad();
                    // pizza.Display();
                    break;

                case "2":     // Pasta operations
                    Console.Clear();
                    pasta = new Pasta();
                    pasta.InitLoad();
                    break;

                case "3":     // Display of order summary
                    Console.Clear();
                    OrderSummary(pizza, pasta);
                    pizza = null;
                    pasta = null;
                    break;

                default:
                    Console.Clear();
                    break;
                }
            } while (oprInput != "0");
        }