create a nested structure in c++ for Arduino

I'm trying to build an attendance management system with a fingerprint.
and now I'm faced with this problem,
I’ve 25 persons and I need to save their entrance time (year, month, hour, minutes) and their exit time (year, month, ...) and compare with their standard Enter/Exit time.
for example, for an imaginary guy like Jack, initially I’ve to set Entrance/Exit time in week. like this,
Sunday Monday .... Friday
Enter Exit Enter Exit .... Enter Exit
7AM 15PM 9AM 16PM .... 7AM 18PM
This is what he should come in an ordinary week.
And then in Sunday morning I’ve to register and save his coming time and so on!
So in this problem we need to sets of variables first one for recording standard time for any person and second of for every day Entrance/Exit Time.
And my question is how to define these set of variables????
Thank you for the time you spent reading my problem.
Best regard
Abolfazl Nejatian