
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
If a two-digit number $AB$ in base 20 (considered numbers with digits $0$ to $19$) is reversed to form another two-digit number $BA$, and the lesser of these two numbers is subtracted from the greater, what must be a prime factor of the difference assuming $A \neq B$ and both $A$ and $B$ are less than 20?

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