1. Divide the set of positive even numbers $\{2,4,6, \cdots\}$ into groups in ascending order, with the $n$-th group containing $3 n-2$ numbers:
$$
\{2\},\{4,6,8,10\}, \quad\{12,14,16,18,20,22,24\}, \cdots
$$

Then 2018 is in the $\qquad$ group.