
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
In quadrilateral $ABCD$, $AD$ is parallel to $BC$. Choose one of the following conditions: ① $AB$ is parallel to $CD$; ② $AB = CD$; ③ $\angle A = \angle C$; ④ $\angle B = \angle C$, which can make quadrilateral $ABCD$ a parallelogram. The number of the condition is ______.

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