#include <bits/stdc++.h>
using namespace std;
double a[1001];
int main(void) {
  int n;
  double m;
  double ans = 0;
  scanf("%d", &n);
  for (int i = 1; i <= n; i++) {
    scanf("%lf", &m);
    a[i] = m;
  }
  sort(a + 1, a + 1 + n);
  for (int i = 1; i <= n; i++) {
    if (i == 1)
      ans = a[i];
    else {
      ans = (ans + a[i]) / 2.0;
    }
    sort(a + i + 1, a + n + 1);
  }
  printf("%.1lf", ans);
  return 0;
}
