using System;

using System.Text.RegularExpressions;

public class Program

{

    public static void Main()

    {

        var testInput = new [] { "mc8jr3cfsdckz-kpdbcxt58rwv24", "mctr810qspwzy54kbjk89sg3wqj4",

                                "https://attackerwebsite.com/callback", "definitely not a subdomain" };

        foreach (var input in testInput)

        {

            Console.WriteLine("{0}: IsValid: {1}", input, IsTssdValid(input));

        }

    }

    public static bool IsTssdValid(string tssd)

    {

        var regex = new Regex(@"^[a-zA-Z0-9-]+$");

        if (regex.IsMatch(tssd))

        {

            return true;

        }

        return false;

    }

}