
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 $\{a_n\}$ whose sum of the first $n$ terms is $S_n = 1 - 5 + 9 - 13 + 17 - 21 + \ldots + (-1)^{n+1}(4n-3)$, calculate the value of $S_{15} + S_{22} - S_{31}$.

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