
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
Twelve stones are arranged in a straight line and are counted in pairs from left to right as $1, 2, 3, \ldots, 6$, and then from right to left, so that the pair previously counted as 5 is counted as 7. The pattern is continued to the left until the pair previously counted as 1 is counted as 13. The pattern then reverses so that the stone originally counted as 2 is counted as 14, 3 as 15, and so on. The counting continues in this manner. Which of the original pairs of stones is counted as 135? Express your answer as a single digit which corresponds to the first digit assigned to that pair.

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