
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
Define the set operation: A*B={z|z=xy, x∈A, y∈B}. Let A={1,2}, B={a,2}, if the set A*B contains exactly 3 elements, then the set of possible values for a is.

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