#include <bits/stdc++.h>
using namespace std;

int main(){
	int n;
	cin >> n;
	double v[n];
	for(int i = 0;i < n;i++) cin >> v[i];
	sort(v,v+n);
	for(int i = 1;i < n;i++){
		v[i] =(double)(v[i]+v[i-1])/2.0;
	}
	cout << v[n-1];
	return 0;
}