problem with recursion

[vegetax]

How can i use a counter inside the recursive function?
This code gives me the error 'local variable 'c' referenced before
assignment'

 #!/usr/bin/python
 from os import listdir
 from os.path import isdir,join,basename
 import HTMLgen
 
 dirpath = '/devel/python/html/test'
 COUNTER = 0 

 def rec(f):
     res = []
     COUNTER += 1 
     for ele in listdir(f):
         res.append(ele)
         ele = join(f,ele)
         if isdir(ele):
            res.append(rec(ele))
     return res
 
 print HTMLgen.List(rec(dirpath))