#include<iostream>
#include<algorithm>
using namespace std;
int main(){
  int n,i;double f,s;cin >> n;
  double a[n];
  for (i=0;i<n;i++) cin >> a[i];
  sort(a,a+n);
  f = a[0];
  for (i=1;i<n;i++) f = (f+a[i])/2;
  cout << f << endl;
}