#include <bits/stdc++.h>
using namespace std;
using ll = unsigned long long;
using ld = long double;
using vi = vector<int>;
using vll = vector<ll>;
using P = pair<int, int>;
const int INF = 1e9;
const ll INFLL = 1e18;
const int MOD = 1e9 + 7;
const int NIL = -1;
const ld PI = acos(-1);
int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  cout << fixed << setprecision(6);
  int n;
  cin >> n;
  vector<ld> v(n);
  for (int i = 0; i < (n); ++i) cin >> v[i];
  sort(v.begin(), v.end());
  list<ld> li;
  for (int i = 0; i < (n); ++i) li.push_back(v[i]);
  for (int i = 0; i < (n - 1); ++i) {
    ld t1 = li.front();
    li.pop_front();
    ld t2 = li.front();
    li.pop_front();
    li.push_back((t1 + t2) / 2);
  }
  cout << li.front() << endl;
  return 0;
}
