#include <bits/stdc++.h>
using namespace std;
int main() {
  long long n;
  cin >> n;
  vector<double> v(n);
  vector<double> v2(n);
  for (long long i = 0; i < n; i++) cin >> v[i];
  sort(v.begin(), v.end());
  for (long long k = 0; k < n - 1; k++) {
    for (long long i = 1; i < n; i++) v2[i - 1] = 0.5 * (v[i - 1] + v[i]);
    for (long long i = 0; i < n; i++) v[i] = v2[i];
  }
  cout << v[0] << endl;
  return 0;
}
