#include <bits/stdc++.h>
using namespace std;
void solve() {
  long long n;
  cin >> n;
  long long a[n];
  for (auto& i : a) cin >> i;
  ;
  sort(a, a + n);
  float ans = (a[0] + a[1]) / 2;
  for (long long i = 2; i < n; i++) {
    ans = (ans + a[i]) / 2;
  }
  cout << ans << "\n";
}
int32_t main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  cout << setprecision(15) << fixed;
  long long t = 1;
  for (long long i = 1; i <= t; i++) {
    solve();
  }
  return 0;
}
