using System;

using System.Text.RegularExpressions;

public class Program

{

    public static void Main()

    {

        var domain = "gsk_dev.com";

        var regexText = $"^(([0-9A-Za-z*\\-_])+\\.)*([0-9A-Za-z\\-_])+\\.{Regex.Escape(domain)}$";

        Console.WriteLine(regexText);

        var regex = new Regex(regexText);

        var test = "dev.gsk_dev.com";

        var match = regex.Match(test);

        if(match.Success)

        {

            Console.WriteLine("yep");

            Console.WriteLine(test);

        }

        else

        {

            Console.WriteLine("nop");

        }

    }

}