using System;

using System.Net;

using System.IO;

using System.Xml;

public class Program

{

    public static void Main()

    {

        var sitemap_url = "https://www.lmca.org/sitemap.xml";

        string xmlStr;

        using(var wc = new WebClient()) {

            xmlStr = wc.DownloadString(sitemap_url);

        }

        var xmlDoc = new XmlDocument();

        xmlDoc.LoadXml(xmlStr);

        foreach (XmlElement url in xmlDoc.GetElementsByTagName("urlset")) {

            foreach (XmlElement urlc in url.GetElementsByTagName("loc")) {

                string urlocation = urlc.InnerText;

                HttpWebRequest myHttpWebRequest = (HttpWebRequest)WebRequest.Create(urlocation); 

                // Sends the HttpWebRequest and waits for a response.

                HttpWebResponse myHttpWebResponse = (HttpWebResponse)myHttpWebRequest.GetResponse(); 

                if (myHttpWebResponse.StatusCode != HttpStatusCode.OK) {

                    Console.WriteLine("Url not working: " +  urlocation);

                }

            }

        }

    }

}