
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
Let P, A, B, C be four points on the surface of a sphere O, with PA, PB, PC being mutually perpendicular, and PA = 1, PB = $\sqrt{2}$, PC = $\sqrt{3}$.  
Then, the surface area of sphere O is $\boxed{9\pi}$.

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