using System;

using System.Collections.Generic;

using System.Linq;

​

class Product

{

    public int Id { get; set; }

    public string Name { get; set; }

    public decimal Price { get; set; }

}

​

class Program

{

    private static List<Product> products = new List<Product>();

    private static int nextId = 1;

​

    static void Main(string[] args)

    {

        bool exit = false;

​

        while (!exit)

        {

            Console.WriteLine("\n--- Product Management System ---");

            Console.WriteLine("1. Add Product");

            Console.WriteLine("2. List All Products");

            Console.WriteLine("3. Find Most Expensive Product");

            Console.WriteLine("4. Exit");

            Console.Write("Select an option (1-4): ");

​

            string choice = Console.ReadLine();

            switch (choice)

            {

                case "1":

                    AddProduct();

                    break;

                case "2":

                    ListAllProducts();

                    break;

                case "3":

                    FindMostExpensiveProduct();

                    break;

                case "4":

                    exit = true;

                    break;

                default:

                    Console.WriteLine("Invalid choice. Please select a valid option.");

                    break;

            }

        }

    }

​

    private static void AddProduct()

    {

    }

​

    private static void ListAllProducts()

    {

    }

​

    private static void FindMostExpensiveProduct()

    {

    }

}