var officeCacheDir = ConfigurationManager.AppSettings[OfficeCacheFolderKey];
var maxAgeMinutes = int.Parse(ConfigurationManager.AppSettings[LastAccessTimeMinutesBeforeDeleteKey]);

while (true)
{
    string[] files = Directory.GetFiles(officeCacheDir).Where(file => Regex.IsMatch(file, @"^.+\.(FSD|FSF)$")).ToArray();
    Console.WriteLine("Found {0} files", files.Length);
    var deletedCount = 0;
    foreach (string file in files)
    {
        var fi = new FileInfo(file);
        if (fi.LastWriteTime < DateTime.Now.AddMinutes(-maxAgeMinutes))
        {
            try
            {
                fi.Delete();
                Console.WriteLine("Deleted {0}", fi.FullName);
                deletedCount++;
            }
            catch (Exception)
            {
                Console.WriteLine("Failed to delete {0}, probably being used.", fi.FullName);
            }
        }
    }

    Console.WriteLine("Deleted Totally {0} files this iteration", deletedCount);
    Console.WriteLine("Sleeping for 1 minute, safe to close application now.");
    Thread.Sleep(60 * 1000);
}