
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
Write all the natural numbers from 1 to 1988 on the blackboard. Perform operations \( A \) and \( B \) on these numbers repeatedly in the following sequence: first \( A \), then \( B \); repeat with \( A \), then \( B \), and so on. Operation \( A \) subtracts the same natural number from each number on the blackboard (different instances of operation \( A \) can subtract different numbers). Operation \( B \) erases two numbers from the blackboard and replaces them with their sum. Continue this process until after one application of operation \( B \), only one non-negative number remains on the blackboard. What is this number?

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