
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
The KML airline operates shuttle services between some cities such that from any city, you cannot directly reach more than three other cities. However, with at most one transfer, you can travel from any city to any other city. What is the maximum number of cities between which the planes operate?

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