using System;

public class Program

{

    public static void Main()

    {

        while (true)

        {

            Console.WriteLine("Main Menu:");

            Console.WriteLine("1. Add Item to Order");

            Console.WriteLine("2. Review Current Order");

            Console.WriteLine("3. Checkout");

            Console.WriteLine("4. Exit");

​

            Console.Write("Please select an option: ");

            string choice = Console.ReadLine();

​

            switch (choice)

            {

                case "1":

                    AddItemToOrder();

                    break;

                case "2":

                    ReviewCurrentOrder();

                    break;

                case "3":

                    Checkout();

                    break;

                case "4":

                    Console.WriteLine("Thank you for your visit. Goodbye!");

                    return;

                default:

                    Console.WriteLine("Invalid option. Please try again.");

                    break;

            }

        }

    }

​

    static void AddItemToOrder()

    {

        Console.WriteLine("Menu:");

        Console.WriteLine("1. Burger - $10.99");

        Console.WriteLine("2. Pizza - $12.99");

        Console.WriteLine("3. Salad - $7.99");

        Console.WriteLine("4. Pasta - $9.99");

        Console.WriteLine("5. Sandwich - $8.99");

​

        Console.Write("Enter the item number you want to order: ");

        if (int.TryParse(Console.ReadLine(), out int itemNumber))

        {

            if (itemNumber >= 1 && itemNumber <= 5)

            {

                Console.Write("Enter the quantity you want to order: ");

                if (int.TryParse(Console.ReadLine(), out int quantity) && quantity > 0)

                {

                    // TODO: Add item to order and quantity

                    Console.WriteLine($"{quantity} item(s) added to the order.");

                }

                else

                {

                    Console.WriteLine("Invalid quantity. Please enter a valid quantity.");

                }

            }

            else

            {

                Console.WriteLine("Invalid item number. Please select a valid item number.");

            }

        }

        else

        {

            Console.WriteLine("Invalid input. Please enter a valid item number.");

        }

    }

​

    static void ReviewCurrentOrder()

    {

        // TODO: Display current order with item names, quantities, and subtotal for each item

        Console.WriteLine("Current Order:");

    }

​

    static void Checkout()

    {

        // TODO: Calculate total cost including tax and display final bill

        Console.WriteLine("Checkout:");

    }

    }

​