
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
In order to estimate the number of fish in a pond, initially 2,000 fish were caught, marked (without affecting their survival), and then released back into the pond. After some time, 500 fish were caught again, of which 40 were marked. Based on the data provided, estimate the total number of fish in the pond.

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