#include<bits/stdc++.h>
using namespace std;
int main(){
int n;
  cin >>n;
  vector<int>v(n);
  for(int i=0;i<n;++i)
    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("%.8f",ans);
}
