#include <bits/stdc++.h>
using namespace std;

#define MAX 50

int main() {
	int N, v[MAX];
	cin >> N;
	for (int i = 0; i < N; i++) cin >> v[i];
	sort(v, v + N);
	double X = v[0];
	for (int i = 1; i < N; i++) X = (X + v[i]) / 2;
	cout << X << endl;
	return 0;
}