using System.Text.RegularExpressions;

using System.Net;

using System;

public class Program

{

    public static void Main()

    {

            Console.WriteLine("Su IP pública: "+PublicIP());

    }

    public static string PublicIP(){

        string ExternalIP;

        ExternalIP = new WebClient().DownloadString("http://checkip.dyndns.org/");

        ExternalIP = new Regex(@"\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}").Matches(ExternalIP)[0].ToString();

        return ExternalIP;

    }

}