#include<bits/stdc++.h>
using namespace std;
long long n,a[300001],sum;
double ans;
int main(){
	cin>>n;
	for (int i=1;i<=n;i++) cin>>a[i];
	sort(a+1,a+n+1);
	for (int i=n;i>=1;i--){
		sum+=a[i];
		if ((sum*sum*1.0)/(n-i+1)>ans) ans=(sum*sum*1.0)/(n-i+1);
	}
	printf("%.8lf",ans);
}