using System;

​

    class User

{

    private static int counter = 0;

    public User()

    {

        counter++;

    }

    public static void DisplayCounter()

    {

        Console.WriteLine(counter);

    }

}

class Program

{

   public static void Main(string[] args)

    {

        User user1 = new User();

        User user2 = new User();

        User user3 = new User();

        User user4 = new User();

        User user5 = new User();

        User.DisplayCounter(); // 5

    }

}

​