using System;

using System.Collections.Specialized;

public class Program

{

    public static void Main()

    {

        NameValueCollection list = new NameValueCollection();

        list["key1"] = "value1";

        list["key2"] = "valuex";

        list["key3"] = "valuey";

        list["key4"] = "valuez";

        list["key5"] = "value5";

        Console.WriteLine(list["key1"]);

        Console.WriteLine(list["key2"]);

        Console.WriteLine(list["key3"]);

        Console.WriteLine(list["key4"]);

        Console.WriteLine(list["key5"]);

        Console.WriteLine(list["key6"]);

        Console.WriteLine(list["key6"]?? "Nulo");

    }

}