#include<iostream>
#include<string>
#include<string.h>
#include<algorithm>
#include<stdio.h>
#include<cmath>
#include<vector>
#include<utility>
#include<stack>
#include<queue>
#include<list>
#include<bitset>

#define FOR(i, a, b) for(int i=(a);i<=(b);i++)
#define RFOR(i, a, b) for(int i=(a);i>=(b);i--)
#define MOD 1000000007
#define INF 1000000000

using namespace std;


int main(void) {
	int n;
	int a[1001];
	double ave;

	cin >> n;
	FOR(i, 0, n-1) {
		cin >> a[i];
	}
	sort(a, a + n);
	if (n % 2 == 1) {
		ave = a[n / 2];
	}
	else {
		ave = (double)(a[n / 2] + a[n / 2 - 1]) / 2.0;
	}
	printf("%.2lf\n", ave);
	return 0;
}