
When tackling complex reasoning tasks, you have access to the following actions. Use them as needed to progress through your thought process.

[ASSESS]

[ADVANCE]

[VERIFY]

[SIMPLIFY]

[SYNTHESIZE]

[PIVOT]

[OUTPUT]

You should strictly follow the format below:

[ACTION NAME]

# Your action step 1

# Your action step 2

# Your action step 3

...

Next action: [NEXT ACTION NAME]


system
Given a sequence $\{a_n\}$ with a sum of the first $n$ terms denoted as $S_n$, which satisfies $S_n=-n^2+7n$ (where $n \in \mathbb{N}^*$).

(I) Find the general formula for the sequence $\{a_n\}$.  
(II) Find the maximum value of $S_n$.

Present the answer in LaTex format: \boxed{Your answer}
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