
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
On January 27, 2017, the first phase of Harbin Metro Line 3 was put into operation. Four students, A, B, C, and D, decided to take the subway to Chengxiang Road, Haxi Station, and Harbin Street. Each person can only go to one place, and at least one person must go to Haxi Station. The number of different touring plans is \_\_\_\_\_\_.

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