using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using System.Web;

public class Program

{

    public static void Main()

    {

        var page0 = new Uri("http://www.example.com/page0");

        Console.WriteLine("Page 0: {0}", page0);

        var page1 = new Uri("http://www.example.com/page1?paramA=foo&paramB=bar&returnUrl=" + HttpUtility.UrlEncode(page0.ToString()));

        Console.WriteLine("Page 1: {0}", page1);

        var page2 = new Uri("http://www.example.com/page2?paramC=baz&paramD=qux&returnUrl=" + HttpUtility.UrlEncode(page1.ToString()));

        Console.WriteLine("Page 2: {0}", page2);

        Console.WriteLine();

        var page2ReturnUrl = HttpUtility.ParseQueryString(page2.Query)["returnUrl"];

        Console.WriteLine("Return to page 1 from page 2: {0}", page2ReturnUrl);

        var page1ReturnUrl = HttpUtility.ParseQueryString(page1.Query)["returnUrl"];

        Console.WriteLine("Return to page 0 from page 1 : {0}", page1ReturnUrl);

    }

}