using System;

using System.Text.RegularExpressions;

​

public class Program

{

    public static void Main()

    {

        string input = "This {is} a {test}...";

        String titleWithOPunch = Regex.Replace(input, @"[^a-zA-Z0-9]", String.Empty);

        titleWithOPunch = Regex.Replace(titleWithOPunch, @"</?\w+((\s+\w+(\s*=\s*(?:"".*?""|'.*?'|[^'"">\s]+))?)+\s*|\s*)/?>", String.Empty);

        //string output = Test(input);

        Console.WriteLine(titleWithOPunch);

    }

}