using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        string[] items = { "a", "b","c","d","e","f","g","a" };

​

        List<string> itemlist = new List<string>(items);

        int? itemwindow = 3;

        itemlist.GetRange(itemlist.Count-itemwindow.Value,itemwindow.Value).ForEach( d => Console.WriteLine(d.ToString()));

    }

}