
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
Two ferries travel between two opposite banks of a river at constant speeds. Upon reaching a bank, each immediately starts moving back in the opposite direction. The ferries departed from opposite banks simultaneously, met for the first time 700 meters from one of the banks, continued onward to their respective banks, turned back, and met again 400 meters from the other bank. Determine the width of the river.

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