##include <bits/stdc++.h>

using namespace std;

int main (){
	int n;
  	double t=0.0;
  
  	cin>>n;
  
  	vector<int> v(n);
   
  	for(int i=0;i<n;i++){
    	cin>>v.at(i);
     }
	sort(v.begin(), v.end());
  	
  	for(int i=0;i<n-1;i++){
    	t=((double)v.at(i)+(double)v.at(i+1))/2.0;
      	v.at(i+1)=t;
    	
    }
  	 cout << fixed << setprecision(50);
  	 cout<<t<<endl;
}