using System;

public class Program

{

    public static void Main()

    {

        Uri absoluteUri = new Uri("http://www.kurtki54.ru/catalog/vetrovka.html");

        string rel = "catalog/vetrovka/ast-1523.html";

        string browser = "http://www.kurtki54.ru/catalog/vetrovka/ast-1523.html";

        Uri combinedUri = new Uri(absoluteUri, rel);

        Console.WriteLine("browser: " + browser);

        Console.WriteLine("dotnet : " + combinedUri.ToString());

    }

}