using System;

using System.IO;

using System.Linq;

public class Program

{

    public static void Main()

    {

        string directoryPath = Path.GetDirectoryName(@"c:\level0\level1\level2\filename.ext");

​

        string folder = directoryPath.Split(Path.DirectorySeparatorChar).Last();

        Console.WriteLine(folder);

    }

}