string dirPath = @"D:\App1";

            List<string> dirs = new List<string>(Directory.GetDirectories(dirPath, "*", System.IO.SearchOption.AllDirectories));
            foreach (var dir in dirs)
            {
                Console.WriteLine("{0}", dir);
            }
            Console.WriteLine("{0} directories found.", dirs.Count);

string dirPath = @"D:\App1";

List<string> dirs = ListDirectory(dirPath);

private static List<string> ListDirectory(string dirPath)
        {
            List<string> dirs = new List<string>(Directory.EnumerateDirectories(dirPath));
            List<string> result = new List<string>();
            foreach (var dir in dirs)
            {

                result.Add(string.Format("{0}", dirPath + "\\" + dir.Substring(dir.LastIndexOf("\\") + 1)));
                Console.WriteLine("{0}", dirPath + "\\" + dir.Substring(dir.LastIndexOf("\\") + 1));

                result.AddRange(ListDirectory(dir));
            }
            return result;
        }