The answer should be none of the above
Take windows 10 for example
It has cmd and desktop and icons and menus
There were
balls but we took
balls out, so there are now
balls. We add
balls and now we have
balls.
The program that computes this (I will use python as language has not been specified is the following):
n, a, b = int(input()), int(input()), int(input())
print(f"There are {n-a+b} balls in the box")
# Hope this helps
It is the USB port..............................................