using System;

using System.Text.RegularExpressions;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var match = Regex.Matches("<title>[FirstName] [SecondName] (@[Username]) on [Site]</title>", @"\(([^)]*)\)").OfType<Match>().LastOrDefault().ToString();

        match.Dump();

    }

}