I need to stop using a lot of lines, this one resumes it all.

Very clean solution

good solution

the python reads all the line becaue all in same line and same interpretting so python read it if it another line there would be an eror

nice

" Please keep in mind that the test cases ensure that the number of people in the bus is always >= 0. "

But this condition: "So the return integer can't be negative." is not fulfilled.
If the last number in the test would be 100, for example, this code returns negative value

Yes, if you try using the stop variable after the list comprehension, it will raise a NameError exception since it is not declared on the current scope!

I understand, so does that mean that we can only use it inside the for loop?

The stop variable is defined in the list comprehension scope (at the 'for xxx in' part), it's 100% valid and shouldn't raise any VSC errors.

simple but effective

good!

Nice, more compact than mine with a similar idea.