#include <bits/stdc++.h>
using namespace std;
int32_t main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long n;
  cin >> n;
  vector<long long> v(n);
  for (long long i = 0; i < n; i++) {
    cin >> v[i];
  }
  sort(v.begin(), v.end());
  long double res = (v[0] + v[1]) / 2.0;
  for (long long i = 1; i < n; i++) res += (res + v[i]) / 2.0;
  cout << res;
  return 0;
}
