/// <summary>
/// Put your own code here to get the files to be concatenated.
/// </summary>
static string[] GetFiles()
{
  DirectoryInfo dirInfo = new DirectoryInfo("../../../../../PDFs");
  FileInfo[] fileInfos = dirInfo.GetFiles("*.pdf");
  ArrayList list = new ArrayList();
  foreach (FileInfo info in fileInfos)
  {
    // HACK: Just skip the protected samples file...
    if (info.Name.IndexOf("protected") == -1)
      list.Add(info.FullName);
  }
  return (string[])list.ToArray(typeof(string));
}