#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vi = vector<int>;
using vvi = vector<vi>;
using vd = vector<double>;
int main() {
  int n;
  cin >> n;
  vd v(n);
  for (int i = 0; i < n; i++) cin >> v[i];
  sort(v.begin(), v.end());
  for (int i = 0; i < n; i++) {
    v[i] = (v[i - 1] + v[i]) / 2;
  }
  cout << v[n - 1] << endl;
}
