using System;

using System.Linq;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        string s = "http://nowatermark.ozone.ru/s3/multimedia-p/6000001033.jpg";

            var val = s.Split('/').TakeLast(3).Aggregate((i, j) => i + "/" + j);

            Console.WriteLine(val);

    }

}