
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 string of decorative lights is made up of bulbs connected in series, with 20 bulbs per string. If any bulb is damaged, the entire string of lights will not light up. Calculate the number of possibilities that a string of lights does not light up due to bulb damage.

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