
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
Iveta sequentially wrote natural numbers consisting of the digits 1, 3, 5, and 7. She used no other digits, proceeded in ascending order from the smallest number, and did not omit any number. She wrote the numbers consecutively to form an exceptionally long number:

$$
1357111315173133 \ldots
$$

What digit is at the 1286th position in this number?

(E. Novotná)

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