#include <bits/stdc++.h>
using namespace std;
#define rep(i,n)=for(int i=0; i<n; i++);
using ll=long long;
int  main(){
int N;
cin>>N;
vector<double>data(N);
 rep(i,N){
     cin>>data.at(N);
 }
 sort(data.begin(),data.end());
double answer=data.at(0);
for(int i=1; i<N+1; i++){
answer=(answer+data.at(i))/2;
}
cout<<answer<<endl;
 }
