#include<cstdio>
#include<algorithm>
int n,a[60];
int main() {
	scanf("%d",&n);
	for (int i=1; i<=n; ++i) scanf("%d",a+i);
	std::sort(a+1,a+n+1);
	double t=a[1];
	for (int i=2; i<=n; ++i) t=(t+a[i])/2;
	printf("%.7lf",t);
	return 0;
}