#include<iostream>
#include<algorithm>
using namespace std;
int n;
double v[51];
int main(){
	cin>>n;
	for(int i=1;i<=n;i++)
		cin>>v[i];
	sort(v+1,v+n+1);
	for(int i=2;i<=n;i++)
		v[i]=(v[i]+v[i-1])/2;
	cout<<v[n];
	cout<<"\n"; 
	return 0;
}