#include <iostream>
#include <iomanip>
#include <algorithm>
#include <vector>
using namespace std;
int main(void) {
	int n;
	cin >> n;
	vector<double> a(n);
	for (int i = 0; i < n; ++i) cin >> a[i];
	sort(a.begin(), a.end());
	double mid;
	if (n % 2 == 1) mid = a[n / 2];
	else mid = (a[n / 2 - 1] + a[n / 2]) / 2;
	cout << fixed << setprecision(10) << mid << endl;
	return 0;
}