
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
There are the following four propositions:
1. The converse of "If $b=3$, then $b^2=9$";
2. The negation of "The areas of congruent triangles are equal";
3. "If $c \leq 1$, then $x^2 + 2x + c = 0$ has real roots";
4. The contrapositive of "If $A \cup B = A$, then $B \subseteq A$".

Among these, the numbers of the true propositions are.

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