描述

Given a sequence of N nonnegative integers. Let's define the median of such sequence. If N is odd the median is the element with stands in the middle of the sequence after it is sorted. One may notice that in this case the median has position (N+1)/2 in sorted sequence if sequence elements are numbered starting with 1. If N is even then the median is the semi-sum of the two "middle" elements of sorted sequence. I.e. semi-sum of the elements in positions N/2 and (N/2)+1 of sorted sequence. But original sequence might be unsorted.

Your task is to write program to find the median of given sequence.

输入

The first line of input contains the only integer number N - the length of the sequence. Sequence itself follows in subsequent lines, one number in a line. The length of the sequence lies in the range from 1 to 250000. Each element of the sequence is a positive integer not greater than 2^32 - 1 inclusive.

输出

You should print the value of the median with exactly one digit after decimal point.

OpenJudge - 1625:Sequence Median

翻译

描述

给定一个N个非负整数序列。我们来定义这个序列的中值。如果N是奇数，则中位数是排序后位于序列中间的元素。人们可能会注意到，在这种情况下，如果序列元素从1开始编号，那么中值在排序序列中的位置是(N+1)/2。如果N是偶数，那么中值就是排序序列中两个“中间”元素的半和。即排序序列中位置N/2和(N/2)+1的元素的半和。但是原始序列可能是无序的。

你的任务是编写程序，找出给定序列的中位数。

输入

输入的第一行包含唯一的整数N——序列的长度。序列本身跟随其后的行，一行中的一个数字。该序列的长度范围是1 ~ 250000。序列的每个元素都是一个不大于2^32 - 1(含2^32 - 1)的正整数。

输出

你需要输出小数点后恰好有一位的中位数值。