About HKG Airport Express Travel Pass

Hi, I'll be arriving in HK in Dec 1 at exactly 10 pm, assuming that I use my first AETP on that day when is the expiration date of the three day unlimited mtr pass? Is it Effective Dec 3 at 00:01 counting as 3 days? Or is it by counting Day 1 in time in which it will start from Dec 1 of 10 pm to Dec 2 of 10 pm which is counted as the 24hr/day one? I need to ensure that it will end on my last day which is Dec 4.