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".

It tries to be warm in September.
unacceptable

Ellen conferred with Helen.
acceptable

A critic thinks that every book is readable.

acceptable