#include <bits/stdc++.h>
#pragma GCC optimize("O3")
using namespace std;
using ll = long long;
using vl = vector<ll>;
using vc = vector<char>;
using vvl = vector<vector<ll>>;
using vvc = vector<vector<char>>;
ll n, k, m, M = 1e9 + 7;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  cin >> n;
  vl a(n);
  for (ll i = 0; i < ll(n); i++) cin >> a[i];
  sort(a.begin(), a.end());
  double r = (a[0] + a[1]) / 2;
  for (int i = 2; i < n; i++) {
    r = (r + a[i]) / 2;
  }
  cout << r << endl;
}
