
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
For a proposition $p$ and its four forms (original proposition, converse, negation, and contrapositive), the number of true propositions is denoted as $f(p)$. Given the proposition $p$: "If two lines $l1: a1x + b1y + c1 = 0$ and $l2: a2x + b2y + c2 = 0$ are parallel, then $a1b2 - a2b1 = 0$." Then, $f(p) = \boxed{2}$.

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