using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

        Potato t = new Potato("yolo");

        List<Potato> e = new List<Potato>();

        e.Add((Potato)null);

        e.Add(t);

        Console.WriteLine(e.Count);

    }

    class Potato

    {

        string y;

        int v;

        public Potato(string f, int i=0)

        {

            y=f;

            v=i;

        }

        public void write()

        {

            Console.WriteLine(y+v); 

        }

    }

}