Throwback to my first university exam last fall semester when I got my exam times confused (thought 14:00 pm was 4:00pm instead of 2:00pm for some reason) and showed up an hour late. My prof was really kind and understanding so he still let me write the exam, and I did better than I expected xd.
There are 2 types of clocks; the 12-hour and the 24-hour standards. Since a 24-hour-(digital)clock runs persistently equivalent to 2-revolutions of a dial-clock, you do not add an AM/PM to it, it will keep continuing till 24:00, then back 00:01. This is called "Military-time"(airports also use this kind of clock, not the 12-hour). So 14:00 is 02:00 PM to 12-hour-clock (or 2 hours pass noon).
It's good that they still let you write the exam(they should, because an exam has a start-time, and also an end-time), but you have less time to perform(including the thinking) before you submit, since you were late. I'm glad you did better than expected
Curious, what program was that?