
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 person, while walking out of town, looked back and noticed a friend who was walking in the same direction but 400 meters behind him. They both walked 200 meters in a straight line while looking at each other. Do you think they should have met? Not at all; after that, there was still a distance of 400 meters between them.

How could this have happened?

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