#include <bits/stdc++.h>
using namespace std;
int main() {
  int N;
  int v[N];
  cin >> N;
  for (int i = 0; i < N; i++) cin >> v[i];
  qsort(v, N, sizeof *v, [](const void* a, const void* b) {
    int arg1 = *static_cast<const int*>(a);
    int arg2 = *static_cast<const int*>(b);
    if (arg1 < arg2) return -1;
    if (arg1 > arg2) return 1;
    return 0;
  });
  double ans = (double)v[0];
  for (int i = 1; i < N; i++) ans = (ans + (double)v[i]) / 2.0;
  cout << ans << endl;
}
