
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 pool has a constantly open drain at the bottom and several water inlets of the same size at the top. When 4 inlets are opened, it takes 5 hours to fill the pool; when 2 inlets are opened, it takes 15 hours to fill the pool. Now, to fill the pool within 2 hours, how many inlets need to be opened at least?

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