#include <iostream>
#include <vector>
#include <algorithm>
#define rep(i,n) for (int i = 0; i < (n); ++i)
using namespace std;
typedef long long ll;

int main() {
  int n;
  cin >> n;
  vector<int> v(n);
  rep(i,n) {
    cin >> v[i];
  } 
  sort(v.begin(), v.end());
  double ans = v[0];
  for(int i = 1; i < n; i++) ans = (ans+v[i])/2;
  printf("%.10f\n", ans);
  return 0;