#include <bits/stdc++.h>
using namespace std;
const int N = 100;
int main() {
  int n, x[N];
  while (~scanf("%d", &n)) {
    for (int i = 0; i < n; i++) scanf("%d", &x[i]);
    sort(x, x + n);
    double ans = x[0];
    for (int i = 1; i < n; i++) ans *= 0.5, x[i] *= 0.5, ans += x[i];
    printf("%f\n", ans);
  }
  return 0;
}
