#include<stdio.h>
int main()
{
	int a,b;
	scanf("%d",&a);
	while(a!=0){
		int c,n=0;
		double r;
		for(b=0;b<a;b++){
			scanf("%d",&c);
			n=n+c;		
		}   r=n/a;
		printf("%.2f\n",r);
		scanf("%d",&a);}
	return 0;
}