
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 the first day of entering the seventh grade, the homeroom teacher wanted all 40 students in the class to get to know each other. They were required to shake hands and introduce themselves to each other. The total number of handshakes among the students was     .

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