
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 there are 2009 numbers arranged in a row with the first number as 1 and the second number as -1, where any three adjacent numbers have the property that the middle number is always equal to the sum of the two numbers before and after it, calculate the sum of these 2009 numbers.

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