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

int main() {
	int N; cin >> N;
	double v[55];
	double sum = 0;
	
	for (int i = 0; i < N; i++) {
		cin >> v[i];
	}
	sort(v, v + N);
	sum = v[0];
	for (int i = 1; i < N; i++) {
		sum = (sum + v[i]) / 2;
	}
	cout << sum;
}