#include <bits/stdc++.h>
using namespace std;
int main(void) {
  int n, i, j;
  double v[1000];
  double sum = 0, temp = 0;
  cin >> n;
  for (i = 0; i < n; i++) {
    cin >> v[i];
  }
  for (i = 0; i < n; i++) {
    for (j = i; j < n; j++) {
      if (v[i] < v[j]) {
        temp = v[i];
        v[i] = v[j];
        v[j] = temp;
      }
    }
  }
  sum = sum + v[0];
  for (i = 1; i < n; i++) {
    sum = (sum + v[i]) / 2;
  }
  cout << sum;
  return 0;
}
