
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
Silly Seal agrees with Clever Crab to double Seal's money every time Seal crosses the bridge by Crab's house, as long as Seal pays an increasing toll of $20$ coins more than the last toll paid each time after crossing the bridge, starting from $20$ coins as the first toll. Sadly, Seal finds that all his money is gone after crossing the bridge three times. Determine the number of coins Seal had at the beginning.

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