#include "bits/stdc++.h"
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());
	for (int i = 1; i < N; i++) {
		A[i] = (A[i - 1] + A[i]) / 2;
	}
	cout << A[N - 1];
}
