using System;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var uri = new Uri("https://www.test.cs/im");

        var uri2 =  new Uri(uri, "/api/haha");

        Console.WriteLine(uri2);

        Console.WriteLine(uri.Append("api/jupijupi"));

        //var baseUri = new Uri("https://www.test.cs/ha/");

        //var uri3 = new Uri(baseUri, "1/");

        //var uri4 = new Uri(uri3, "2"); 

        //Console.WriteLine(uri4);

    }

}

    public static class UriExtensions

    {

        public static Uri Append(this Uri uri, params string[] paths)

        {

            return new Uri(paths.Aggregate(uri.AbsoluteUri, (current, path) => string.Format("{0}/{1}", current.TrimEnd('/'), path.TrimStart('/'))));

        }

    }