
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 sequence 2008, 2009, 1, -2008, ... where each term starting from the second term is equal to the sum of its preceding and succeeding terms. Find the sum of the first 2019 terms of this sequence, denoted as S$_{2019}$\_{}.

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