#include <bits/stdc++.h>
using namespace std;
const int INF = (int)1e10;
void solve() {
  int n;
  cin >> n;
  vector<int> v(n);
  for (int i = 1; i <= n; i++) cin >> v[i];
  sort((v).begin(), (v).end());
  long double sum = v[1];
  for (int i = 1; i <= n; i++) {
    sum = (sum + v[i + 1]) / 2.0;
  }
  cout.precision(10);
  cout << fixed;
  cout << sum;
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0), cout.tie(0);
  int tt = 1;
  while (tt--) {
    solve();
  }
  return 0;
}
