
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
Construct a four-digit number using only the digits 1, 2, and 3. The rules are such that all three digits must be used at least once, and identical digits cannot be adjacent. There are ______ four-digit numbers that meet these criteria.

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