#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  int m;
  cin >> n;
  int a[n];
  for (int i = 0; i < n; i++) {
    cin >> a[i];
  }
  sort(a, a + n);
  double tmp = (a[0] + a[1]) / 2;
  for (int i = 2; i < n; i++) {
    tmp = (tmp + a[i]) / 2;
  }
  if (n == 1) {
    cout << a[0];
  } else
    printf("%.5f", (double)tmp);
}
