
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 $a > 0$, let the function $$f(x)= \frac {2009^{x+1}+2007}{2009^{x}+1}+\sin x \quad (x\in[-a，a])$$ have a maximum value of $M$ and a minimum value of $N$. Then, $M+N= \_\_\_\_\_\_$.

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