Converting hours and minutes in military time to minutes

I have been banging my head over this for about a week and i think im over thinking it. This is what i need done.

Im making a worksheet and need people to enter in a start time and an end time, then i need it to tell me how many hours that is as well as a total of how many minutes all together. Basically i need it to break down in minutes for sure.

But it must have military time only, and if you do enter it in as time i don't want them to put in the colon. And my issue is usually if the time is 2200 to 0100, it gives me a negative, i fixed that but then my minutes are messed up. The hours and minutes can be separated or in the same cell.

Right now i have it as Start hour / minutes
End hour / minutes
total hours / minutes
total minutes all together

Plz give me a hand i'd appreciate it.

Any other questions you have for me, message me, i need this asap..plz

thanks