
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 an arithmetic sequence $\{a_n\}$ with the sum of the first $n$ terms denoted as $S_n$, and it is known that $S_8 > S_9 > S_7$, among the following conclusions:

① $d > 0$; ② $S_{15} > 0$; ③ $S_{16} < 0$; ④ $S_{17} > 0$; ⑤ $S_{10} < S_7$

The correct conclusions are.

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