Five people go to work, and four people are on duty at ordinary times. 12.00- 14.00 ensures that two people are on duty at noon. How to eat in shifts at noon? Normal day shift, no night shift.

It's simple. Five people take turns to rest, that is, everyone works four days every five days. Of the four people who work, two eat at 12.00- 13.00, and two eat at 13.00- 14.00. As for the order, you can draw lots first, and then you can skip class privately with others if you have something to do.

I wish you progress in your studies and go up a storey still higher!