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