
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
For a project, if person A works alone, it takes $a$ days to complete, and if person B works alone, it takes $b$ days to complete. Both $a$ and $b$ are natural numbers. Now, if person B works alone for 3 days, and then A and B work together for 1 day, the project is just completed. The value of $a+b$ is either     or     .

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