Add [END] at the last file

Hi, i have a problem with this function. i can't add the string "[END]" at the last file. for example i have 20 files named from 1 to 20. i want that the 20th at the and of the name have [END]. (file 1,file 2... file 20 [END]).
The problem is that i don't have a fixed number of files :(
How can I do?I must creat a script? if yes how?

---

Reply to #1:
I have sent you the answer to this question by e-mail. But to help others too, I will also write a solution here.

Add the script method to the end of the sequence of methods and copy/paste the following script into the textbox:
if (index == app.itemCount-1)
return item.newBasename + ' [END]';

---

Reply to #2:
Yes,i see it later. Thanks a lot for the help!

---