using System;

using System.Collections.Generic;

using System.Linq;

​

namespace give_me_domain

{

    static class Program

    {

        static void Main(string[] args)

        {

            var t = (new Uri("https://poddomen.domen.ru").DnsSafeHost).Split('.');

            var d = t[t.Count()-2]+'.'+t[t.Count()-1];

            Console.WriteLine(d);

        }

    }

}

​