#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  int a[n + 1];
  for (int i = 1; i <= n; i++) cin >> a[i];
  sort(a + 1, a + 1 + n);
  int x;
  x = (a[1] + a[2]) * 1.0 / 2;
  for (int i = 3; i <= n; i++) {
    x = (a[i] + x) * 1.0 / 2;
  }
  cout << x;
  return 0;
}
