#include <bits/stdc++.h>
using namespace std;
void debug() {}
int main() {
  debug();
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int n;
  cin >> n;
  int a[n];
  for (int i = 0; i < n; ++i) {
    cin >> a[i];
  }
  sort(a, a + n);
  float x;
  if (n == 1) {
    cout << a[0] << endl;
    return 0;
  } else {
    x = ((a[0] + a[1]) / 2);
    for (int i = 2; i < n; ++i) {
      x = ((x + a[i]) / 2);
    }
    cout << x << endl;
  }
  return 0;
}
