
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
Fifteen distinct points are on the circumference of a circle, and one additional central point inside the circle. How many different convex quadrilaterals can be formed under the condition that one vertex must be the central point inside the circle, and the other vertices must be among the fifteen points on the circumference?

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