#!/usr/bin/env python

str = "ABBBCCDDZ"

parts = []
last_char = ''
current_chunk = ''
for i in range(len(str)):
  current_char = str[i]
  if (current_chunk == '') or (last_char == current_char):
    current_chunk = current_chunk + current_char
  else:
    parts.append(current_chunk)
    current_chunk = current_char
  last_char = current_char
if len(current_chunk)>0:
  parts.append(current_chunk)
print parts