12：求平均年龄

#include<iostream>
#include<cstdio>
using namespace std;
int n;
#define rep(i,j,k) for(int i=j;i<=k;i++)
int main()
{
    int sum=0;
    cin>>n;
    int tmp;
    rep(i,1,n)
    {
        cin>>tmp;
        sum+=tmp;
    }
    printf("%.2lf",(double)sum/n);
}