
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
The function \( f(n) \) is an integer-valued function defined on the integers which satisfies \( f(m + f(f(n))) = -f(f(m+1)) - n \) for all integers \( m \) and \( n \). The polynomial \( g(n) \) has integer coefficients and satisfies \( g(n) = g(f(n)) \) for all \( n \). Find \( f(1991) \) and determine the most general form for \( g \).

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