
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
Points $A$ and $B$, located on a circular alley, are connected by a straight highway segment 4 km long, which is the diameter of the circular alley. A pedestrian left home at point $A$ for a walk along the alley. After 1 hour, he realized he had forgotten his keys and asked a neighbor, who is a cyclist, to quickly bring them to him. Through what minimum time can he receive the keys, given that the cyclist's speed on the highway is 15 km/h, on the alley is 20 km/h, and the pedestrian's speed is 6 km/h? The pedestrian can walk towards the cyclist.

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