using System;
using System.Text.RegularExpressions;

public class Test
{
public static void Main()
	{
		String miRuta = "C:\\Users\\JoseCarlos\\Desktop\\mv\\lolo-s001.vmdk";
        Console.WriteLine(miRuta);
        Console.WriteLine(Regex.Replace(miRuta, "[^\\\\]+(?=\\\\[^\\\\]+$)", "lolo"));
	}
}