Your task is to output a single number; the number of ISO weeks that a given date range intersects. To quote Wikipedia:
An average year is exactly 52.1775 weeks long, but this is not about the average.
Input consists of two space-separated ISO dates:
The end date is never before the start date. We'll use the extrapolated Gregorian calendar for simplicity.
Format: input -> output 2015-12-31 2016-01-01 -> 1 (both are within week 53 of 2015) 2016-01-03 2016-01-04 -> 2 (the 3rd is within week 53, and the 4th is in week 1) 2015-12-24 2015-12-24 -> 1 (this single day is of course within a single week)
Your solution should handle dates between