You're given a sentence and your task is to classify whether the sentence is acceptable or not. Any sentence which is grammatically correct, has a naturalistic text, is written by a native speaker and which minimizes superfluous content is acceptable, otherwise unacceptable. If the sentence is acceptable then write "acceptable", otherwise "unacceptable".

I know which book Mag read, and which book Bob discussed after I had.
unacceptable

The branches knocked against the wall.
acceptable

John scratched his arm and the boy who Mary knew did so too.

acceptable