#include <iostream>
using namespace std;
typedef struct LNode {
int data;
struct LNode * next;
}
LNode, * linkList;
void CreateList_R(linkList & L, int n) { //后插法创建单链表
L = new LNode;
L -> next = NULL;
linkList r = L;
for (int i = 0; i < n; i++) {
linkList p = new LNode;
cin >> p -> data;
p -> next = NULL;
r -> next = p;
r = p;
}
}
double GetAverage(linkList L, int n) { //递归求解单链表中的平均值
/**************begin************/
/**************end************/
}
int main() {
int n;
while (cin >> n) {
if (n == 0) break;
linkList L;
CreateList_R(L, n);
L = L -> next; //L指向首元结点
printf("%.2f\n", GetAverage(L, n)); //输出保留两位小数
}
return 0;
}
