#include<io>#include<iostream>
#include<cstring>
#include<algorithm>
#include<iomanip>
using namespace std;
double a[55];
int n;
int main(){
	cin>>n;
	for(int i=1;i<=n;++i)cin>>a[i];
	sort(a+1,a+n+1);
	double ans=a[1];
	for(int i=2;i<=n;++i)ans=(ans+a[i])/2.0;
	cout<<fixed<<setprecision(6)<<ans<<endl;
}