
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
There are four trees standing at the four vertices of a horizontally positioned square. The vertices are equidistant from point $O$ located inside the square. The height of the first tree is $a$, the height of the second tree is $b$, and the height of the third tree is $c$. What is the height of the fourth tree?

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