#include <stdio.h>    
int main() {    
    int n;
	int age;
	int count=1;
	int i=1;
	float sum=0.0;
	printf("你的班级一共有几人\n");
	scanf("%d",&n);
	for(i=0;i<n;i++){
		printf("请输入年龄\n");
		scanf("%d",&age);
		sum+=age;
	}
	double all=sum/i;
	printf("%.2lf\n",all);
    return 0;    
}