#include<bits/stdc++.h>
using namespace std；
int main (){
	int n;
	cin >> n;
	int a[n+1];
	for (int i=1;i<=n;i++)
	cin >> a[i];
	sort(a+1,a+1+n);
	int x;
	x = (a[1]+a[2])*1.0/2;
	for(int i=3;i<=n;i++){
		x = (a[i]+x)*1.0/2;
	}
	cout << x;
	return 0;
}