using System;

using System.Collections;

​

public class Program

{

    static Queue cashier;

    public static void Main()

    {

        Console.WriteLine("Axl John's Kainan");

        cashier = new Queue();

        for (int i = 0; i <= 99; i++){

            Console.WriteLine("");

            Console.WriteLine("Type 'O' to order or type 'R' to receive the order");

            Console.WriteLine("");

            Console.WriteLine("current order:");

            Orders();

            String answer = Console.ReadLine();

            if (answer == "O" || answer == "o"){

                cashier.Enqueue("P100" + i);

            }

            else if (answer == "R" || answer == "r"){

                cashier.Dequeue();

            }

            else{

                Console.WriteLine("");

                Console.WriteLine("Invalid input");

            }

        }

    }

    static void Orders() {

            if (cashier.Count == 0)

            { 

                Console.WriteLine("No orders yet");

            }

            else

            {

                foreach (var order in cashier){

                Console.WriteLine(order);

                }

            }

    }               

}

​