import re
sentence = '''
Tue, 20 August 2019
17:30 - 21:00 CEST
'''
pattern = re.compile(r'\d\d:\d\d')
cnt = 0
wanted = [1,2]
for match in pattern.finditer(sentence):
cnt += 1
if cnt in wanted:
print(match.group())
aW1wb3J0IHJlCgpzZW50ZW5jZSA9ICcnJyAKVHVlLCAyMCBBdWd1c3QgMjAxOQoxNzozMCAtIDIxOjAwIENFU1QgCicnJwpwYXR0ZXJuID0gcmUuY29tcGlsZShyJ1xkXGQ6XGRcZCcpCmNudCA9IDAKd2FudGVkID0gWzEsMl0KCmZvciBtYXRjaCBpbiBwYXR0ZXJuLmZpbmRpdGVyKHNlbnRlbmNlKToKICAgIGNudCArPSAxCiAgICBpZiBjbnQgaW4gd2FudGVkOgogICAgICAgIHByaW50KG1hdGNoLmdyb3VwKCkp