#include <bits/stdc++.h>
using namespace std;
int main() {
  int N;
  cin >> N;
  vector<double> g(N);
  for (int i = 0; i < N; i++) {
    cin >> g[i];
  }
  sort(g.begin(), g.end());
  int sum = (g[0] + g[1]) / 2;
  for (int i = 2; i < N; i++) {
    sum = (sum + g[i]) / 2;
  }
  cout << sum << endl;
}
