static class Tproger
    {
        static string dir = @"C:\Cats\Porno";

        static List<string> GetAllFiles(string dir)
        {
            return Directory.GetFiles(dir, "EDI_*", SearchOption.AllDirectories)
                .Where((x) => new FileInfo(x).Length < 1024 && (x.EndsWith(".eml") || x.EndsWith(".zip"))).ToList();
        }

        static public void Main()
        {
            List<string> resultList = GetAllFiles(dir);
            resultList.Sort(String.Compare);
            resultList.ForEach((x) => Console.WriteLine(x));
        }
    }