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## 문제

Little Ivica received N math grades and wants to calculate their average. He knows that the average of two numbers a and b is calculated as (a + b) / 2, but he still doesn’t know how to do it for multiple numbers. He calculates the average by writing down N grades and repeating the following operations N - 1 times:

1. He chooses two numbers and erases them.
2. He writes down the average of the two chosen numbers.

After precisely N - 1 steps, the only number written down will be the one representing the average grade to Ivica. It is your task to determine the largest average that can be obtained this way.

## 입력

The first line of input contains the integer N (1 ≤ N ≤ 20), the number from the task.

The ith of the following N lines contains the integer Xi (1 ≤ Xi ≤ 5), the ith grade.

## 출력

Output the largest possible average from the task. Your solution is allowed to deviate from the official one for 0.000001.

## 예제 입력 1

4
2
4
5
2


## 예제 출력 1

4.000000


## 예제 입력 2

3
5
5
4


## 예제 출력 2

4.750000


## 예제 입력 3

3
1
3
5


## 예제 출력 3

3.500000


## 힌트

Clarification of the third test case:

Initially, the numbers 1, 3 and 5 are written down.

In the first step, Ivica chooses numbers 1 and 3, erases them and writes down 2. After the first step, 2 and 5 are written down.

In the second step, Ivica chooses the remaining two numbers which average is 3.5.