
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
Xiao Gang's father is a professional fish farmer. He wants to evaluate the total number of fish in his fish pond. He first caught 100 fish, marked each fish, put them back into the water, then caught another 200 fish. Among them, 5 fish had marks. The estimated total number of fish in his pond is ____.

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