
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
Four elevators in a skyscraper, differing in color (red, blue, green, and yellow), move in different directions at different but constant speeds. An observer timed the events as follows: At the 36th second, the red elevator caught up with the blue one (moving in the same direction). At the 42nd second, the red elevator passed by the green one (moving in opposite directions). At the 48th second, the red elevator passed by the yellow one. At the 51st second, the yellow elevator passed by the blue one. At the 54th second, the yellow elevator caught up with the green one. At what second from the start will the green elevator pass by the blue one, assuming the elevators did not stop or change direction during the observation period?



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