
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 $f(x)$ is an odd function defined on $\mathbb{R}$ and for any $x \in \mathbb{R}$, $f(x+3) + f(-x) = 0$. When $x \in (0, 1]$, $f(x) = \sin\left(\frac{\pi x}{2}\right) - 1$. Evaluate the expression $f(2019) + f(2020)$.

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