菜，就多练

#include <iostream>
using namespace std;
const int N=10001;
int n;
int a[N];
double sum=0;
int main(){
    cin>>n;
    for(int i=0;i<=n-1;++i)
    {
        cin>>a[i];
    }
    for(int i=0;i<=n-1;++i)
    {
        sum=sum+a[i];
    }
    printf("%.2f",sum/n);
    
return 0;
}