using System;

using System.Collections.Generic;

​

public class Product

{

    public string Name { get; set; }

    public decimal Price { get; set; }

    public decimal? Discount { get; set; } // Nullable to indicate optional discount

​

    public Product(string name, decimal price, decimal? discount = null)

    {

        Name = name;

        Price = price;

        Discount = discount;

    }

}

​

public class OrderItem

{

    public Product Product { get; set; }

    public int Quantity { get; set; }

​

    public OrderItem(Product product, int quantity)

    {

        Product = product;

        Quantity = quantity;

    }

}

public class Program

{

    public static void Main()

    {

​

​

    }

}