Regex Matches in C#

static void Main(string[] args)
{
  string sample = "Swedish field marshal ... fact that Gustav II father the Thirty Years' War";

  Regex r = new Regex(@"JS_DisplayEntry\((\d*?)\)", RegexOptions.IgnoreCase);

  MatchCollection collection = r.Matches(sample);

  foreach (Match m in collection)
  {
    Console.WriteLine(m.Groups[1].Value);
  }

  Console.ReadLine();
}