
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
On the board, 2017 digits are written. From these digits, several numbers are formed, the sum of the digits of these numbers is calculated, and then the sum of the sums of their digits is subtracted from the sum of all numbers. The resulting number is broken down into digits, and the above operation is repeated again. After performing this operation several times, only one digit remained on the board for the first time. What is this digit?

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