#include <bits/stdc++.h>
using namespace std;
void swap(double v[], int i, int j) {
  double tmp = v[i];
  v[i] = v[j];
  v[j] = tmp;
}
void sort(double v[], int n) {
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n - 1; j++)
      if (v[j + 1] < v[j]) swap(v, j, j + 1);
}
int main() {
  int N, count = 0;
  cin >> N;
  double v[N], blend, sum;
  for (int i = 0; i < N; i++) cin >> v[i];
  sort(v, N);
  for (int i = 1; i < N; i++) {
    if (v[i] / v[0] == 0) count++;
  }
  if (count = N)
    blend = v[0];
  else if (N == 2)
    blend = (v[0] + v[1]) / 2;
  else if (N >= 3) {
    for (int i = 1; i < N; i++) {
      if (i == 1) {
        blend = (v[0] + v[1]) / 2;
        sum = blend;
        blend = 0;
      } else {
        blend += (sum + v[i]) / 2;
        sum = blend;
      }
    }
  }
  cout << blend << endl;
}
