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".

The more Fred is obnoxious, the less you should pay attention to him.
acceptable

I know a boy mad at John.
acceptable

The book of poems with a red cover from Blackwell by Robert Burns takes a very long time to read.

acceptable