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".

Example Input: Those books slide across the table easily.
Example Output: acceptable

Example Input: Calvin had been eating.
Example Output: acceptable

Example Input: Student studies English for 4 hours a day.
Example Output:
unacceptable