
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
A collection of positive odd numbers \(\{1, 3, 5, \cdots\}\) is grouped in ascending order such that the \(n\)-th group has \((2n-1)\) odd numbers:
\(\{1\}\),
\(\{3, 5, 7\}\),
\(\{9, 11, 13, 15, 17\}, \cdots\)

(First group)
(Second group)
(Third group)

Determine in which group 1991 is located.

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