#include <bits/stdc++.h>
using namespace std;
float sum;
long long a[1000005];
void solve() {
  long long n, k;
  cin >> n;
  for (long long i = 1; i <= n; i++) {
    cin >> a[i];
  }
  sort(a + 1, a + n + 1);
  sum = (a[1] + a[2]) / 2;
  for (long long i = 3; i <= n; i++) {
    sum = ((sum + a[i]) / 2);
  }
  cout << sum;
}
signed main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long t = 1;
  while (t--) {
    solve();
  }
  return 0;
}
