
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
A boy tried to align 480 coins in the shape of a triangle, with one coin in the first row, two coins in the second row, and so on. At the end of the attempt, 15 coins were left. How many rows does this triangle have?

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