
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 the sequences $\left\{a_{n}\right\}$ and $\left\{b_{n}\right\}$ satisfy the following conditions:
\[
\begin{array}{l}
a_{1}=-1, b_{1}=2, \\
a_{n+1}=-b_{n}, b_{n+1}=2 a_{n}-3 b_{n} \quad \text{for } n \in \mathbf{Z}_{+}
\end{array}
\]
Find $b_{2015} + b_{2016}$.

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