#include <bits/stdc++.h>
using namespace std;
int asc(const void *a, const void *b) { return *(int *)b - *(int *)a; }
int main() {
  int n;
  double v[55];
  cin >> n;
  for (int i = 0; i < n; ++i) cin >> v[i];
  qsort(v, n, sizeof(double), asc);
  double cnt = v[0];
  for (int i = 0; i < n - 1; ++i) {
    cnt = (cnt + v[i + 1]) / 2;
  }
  cout << cnt << endl;
}
