#include<bits/stdc++.h>
using namespace std;

int main(){
  int n;cin>>n;
  vector<double> v(n);for(int i=0;i<n;i++){cin>>v.at(i);}
  sort(v.begin(),v.end());
  double ans=v.at(0);
  for(int i=1;i<n;++i){
    ans=(ans+v.at(i))/2;
  }
  cout<<ans<<endl;
  return 0;
}