
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
A function $f(x)$ defined on $\mathbb{R}$ satisfies: for any $x, y \in \mathbb{R}$, $f(x + y) = f(x) + f(y) - 2018$ and $f(x) > 2018$ when $x > 0$. Let $M$ and $N$ be the maximum and minimum values of $f(x)$ on $[-2017, 2017]$, respectively. Find the value of $M + N$.

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