
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 athletes start running simultaneously - the first from \( A \) to \( B \), and the second from \( B \) to \( A \). They run at different but constant speeds and meet at a distance of 300 meters from \( A \). After running the track \( AB \) to the end, each of them immediately turns back and meets the other again at a distance of 400 meters from \( B \). Find the length of \( AB \).

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