
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 10 photos, each showing three people from left to right: a son, a father, and the father's sibling. Given that the ten individuals in the middle of the photos (the fathers) are all different, how many distinct people appear in these 10 photos at least?

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