#include<algorithm>
#include<iostream>
#include<cmath>
#include<cstdio>
#include<vector>
using namespace std;
int main(void){
	int N=0;
	cin>>N;
	vector<int>v(N);
	for
	for(int i=0;i<N;i++){
		cin>>v[i];
	}
	sort(v.begin(),v.end());
	double ans=v[0];
	for(int i=1;i<N;i++){
		ans+=v[i];
		ans/=2;
	}
	cout<<ans<<endl;
	return 0;
}