Editorial for COCI '09 Contest 7 #1 Spavanac

Remember to use this editorial only when stuck, and not to copy-paste code from it. Please be respectful to the problem author and editorialist.
Submitting an official solution before solving the problem yourself is a bannable offence.

Just carefully implement the "subtract 45 minutes" operation. The tricky parts are $M < 45$ ~M < 45~ and from 0:00 to 0:45.