
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
A depot has $2020$ boxes, each containing $42$ books. 

David's supervisor instructs him to reorganize all the books so that each new box contains $45$ books. After repacking as many full boxes as possible, how many books will David have left over?

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