Calculation of hours

Good morning people, everything fine ?

I would like to know if it is possible for you to help me calculate a difference between hours.

I have some problems to share so we can find the solution below:

Example 1: 22:00 - 00:00 => 22:00

Example 2: 21:30 - 00:30 => 21:30

Example 3: 23:59 - 03:00 => 20:59

Result I hope to achieve

Example 1 = 02:00

Example 2 = 03:00

Example 3 = 02:59

Can you help me??