Problem Statement

Takahashi is participating in a gymnastic competition.
In the competition, each of 5N judges grades Takahashi's performance, and his score is determined as follows:

• Invalidate the grades given by the N judges who gave the highest grades.
• Invalidate the grades given by the N judges who gave the lowest grades.
• Takahashi's score is defined as the average of the remaining 3N judges' grades.

More formally, Takahashi's score is obtained by performing the following procedure on the multiset of the judges' grades S (|S|=5N):

• Repeat the following operation N times: choose the maximum element (if there are multiple such elements, choose one of them) and remove it from S.
• Repeat the following operation N times: choose the minimum element (if there are multiple such elements, choose one of them) and remove it from S.
• Takahashi's score is defined as the average of the 3N elements remaining in S.

The $i-th (1\leq i\leq 5N)$ judge's grade for Takahashi's performance was X_i points.
Find Takahashi's score.

Input

The input is given from Standard Input in the following format:
N
$X_1 X_2 \ldots X_{5N}$

Output

Print Takahashi's score.
Your answer will be considered correct if the absolute or relative error from the true value is at most 10^{-5}.

Constraints

• $1\leq N\leq 100$
• $0\leq X_i\leq 100$
• All values in the input are integers.

Sample Input 1

1
10 100 20 50 30

Sample Output 1

33.333333333333336

Since N=1, the grade given by one judge who gave the highest grade, and one with the lowest, are invalidated.
The 2-nd judge gave the highest grade (100 points), which is invalidated.
Additionally, the 1-st judge gave the lowest grade (10 points), which is also invalidated.
Thus, the average is $\displaystyle\frac{20+50+30}{3}=33.333\cdots$.
Note that the output will be considered correct if the absolute or relative error from the true value is at most 10^{-5}.

Sample Input 2

2
3 3 3 4 5 6 7 8 99 100

Sample Output 2

5.500000000000000

Since N=2, the grades given by the two judges who gave the highest grades, and two with the lowest, are invalidated.
The 10-th and 9-th judges gave the highest grades (100 and 99 points, respectively), which are invalidated.
Three judges, the 1-st, 2-nd, and 3-rd, gave the lowest grade (3 points), so two of them are invalidated.
Thus, the average is $\displaystyle\frac{3+4+5+6+7+8}{6}=5.5$.
Note that the choice of the two invalidated judges from the three with the lowest grades does not affect the answer.

见题面 Input 部分

见题面 Output 部分