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

int main(){
  int n;cin>>n;
  vector<double> v(n);
  for(auto &i : v) cin>>i;
  sort(v.begin(),v.end());
  double ans=v[0];
  for(int i=1;i<n;i++){
    ans=(ans+v[i])/2;
  }
  cout<<ans<<"\n";
	return 0;
}
  