
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
Two pedestrians started walking at dawn. Each was walking at a constant speed. One walked from point $A$ to point $B$, and the other from point $B$ to point $A$. They met at noon and continued walking without stopping. One arrived at $B$ at 4 PM, and the other arrived at $A$ at 9 PM. At what hour was dawn on that day?

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