What is the maximum value of $-x^2- 8x + 12$?
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
What is the maximum value of $-x^2- 8x + 12$?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
28
What is the maximum value of $-x^2- 8x + 12$?
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