Calculate resolution time

I am trying to calculate how long time it took from creation and until resolution of a task.

The format is: 2016-06-09T14:37:05.000+0200

This is the code:

#!/usr/bin/python
from datetime import datetime
from datetime import timedelta

createdTime = datetime.strptime('2016-06-09T14:37:05.000+0200', '%Y-%m-%dT%H:%M:%S.%f%z')
resolvedTime = datetime.strptime('2016-06-10T10:53:12.000+0200', '%Y-%m-%dT%H:%M:%S.%f%z')

duration = resolvedTime - createdTime

However, I am receiving this error when I run it:

ValueError: 'z' is a bad directive in format '%Y-%m-%dT%H:%M:%S.%f%z'