#include<bits/stdc++.h>
using namespace std;
int n,a[105];
int main()
{
	scanf("%d",&n);
	for(int i=1;i<=n;i++)scanf("%d",&a[i]);
	sort(a+1,a+n+1);
	double ans=a[1];
	for(int i=2;i<=n;i++)ans=(double)(ans+a[i])/2;
	printf("%.10lf",ans);
	return 0;
}