#include <bits/stdc++.h>
using namespace std;
void solve() {
  int n;
  cin >> n;
  double ans = 0;
  vector<int> xs(n);
  for (int i = 0; i < n; i++) {
    cin >> xs[i];
  }
  sort(xs.begin(), xs.end());
  for (int x : xs) {
    ans += x;
    ans /= 2;
  }
  cout << ans << endl;
}
int main() {
  solve();
  cerr << "努力不足ですね！" << endl;
  return 0;
}
