#include <iostream>
#include <vector>
#include <algorithm>
#include <iomanip>

using namespace std;

int main() {
	int n;
	cin >> n;
	vector<double> a(n);
	for (int i = 0; i < n; ++i) {
		cin >> a[i];
	}
	sort(a.begin(), a.end());
	double median = (a[(a.size() - 1) / 2] + a[a.size() / 2]) / 2.0;
	cout << fixed << setprecision(8) << median << endl;
	return 0;
}