#include<cstdio>
#include<algorithm>
using namespace std;
double a[100010];
int main()
{
	int n;
	double ans=0;
	scanf("%d",&n);
	for(int i=1;i<=n;i++)scanf("%lf",&a[i]);
	sort(a+1,a+n+1);
	ans=a[1];
	for(int i=2;i<=n;i++)ans=(ans+a[i])/2;
	printf("%.8lf\n",ans);
}