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Score : $300$ points

### Problem Statement

There are $3N$ participants in AtCoder Group Contest. The strength of the $i$-th participant is represented by an integer $a_i$. They will form $N$ teams, each consisting of three participants. No participant may belong to multiple teams.

The strength of a team is defined as the second largest strength among its members. For example, a team of participants of strength $1$, $5$, $2$ has a strength $2$, and a team of three participants of strength $3$, $2$, $3$ has a strength $3$.

Find the maximum possible sum of the strengths of $N$ teams.

### Constraints

• $1 ≤ N ≤ 10^5$
• $1 ≤ a_i ≤ 10^{9}$
• $a_i$ are integers.

### Input

Input is given from Standard Input in the following format:

$N$
$a_1$ $a_2$ $...$ $a_{3N}$


### Sample Input 1

2
5 2 8 5 1 5


### Sample Output 1

10


The following is one formation of teams that maximizes the sum of the strengths of teams:

• Team $1$: consists of the first, fourth and fifth participants.
• Team $2$: consists of the second, third and sixth participants.

### Sample Input 2

10
1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000


### Sample Output 2

10000000000


The sum of the strengths can be quite large.