
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
In the 100-digit number 12345678901234...7890, all digits in odd positions were crossed out; in the resulting 50-digit number, all digits in odd positions were crossed out again, and so on. The crossing out continued as long as there were digits to cross out. Which digit was crossed out last?

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