
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 that the sequence $\{a\_n\}$ is an arithmetic sequence with a common difference of $-2$, and $a\_3=a\_2+a\_5$.
(I) Find the general term formula of the sequence $\{a\_n\}$.
(II) Find the maximum value of the sum of the first $n$ terms of the sequence, denoted as $S\_n$.

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