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".

Sally started running down the street, but only after José started.
unacceptable

I am not certain about whether he will go or not.
acceptable

The problem disappeared.

acceptable