#include <bits/stdc++.h>
using namespace std;
vector<double> input(int N) {
  int i;
  vector<double> output(N);
  for (i = 0; i < N; i++) cin >> output[i];
  return output;
}
int main() {
  int N, i;
  double result;
  vector<double> V;
  cin >> N;
  V = input(N);
  sort(V.begin(), V.end());
  result = (V[0] + V[1]) / 2;
  for (i = 2; i < N; i++) {
    result = (result + V[i]) / 2;
  }
  cout << result << endl;
  return 0;
}
