
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 mayor of a city wishes to establish a transport system with at least one bus line, in which:
- each line passes exactly three stops,
- every two different lines have exactly one stop in common,
- for each two different bus stops there is exactly one line that passes through both.
Determine the number of bus stops in the city.

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