
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
There are four points \( A, B, C, D \) arranged in order from left to right on a straight line. Using these four points as endpoints, 6 line segments can be formed. The lengths of these 6 line segments are known to be \( 14, 21, 34, 35, 48, 69 \) (units: millimeters). What is the length of the line segment \( \mathrm{BC} \) in millimeters?

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