#include <iostream>

using namespace std;

int main()
{
    int n; cin>>n;
    double average=0;
    double broj_na_clenovi=0;
    for(int i=0; i<n; i++){
        int a;
        cin>>a;
        if(a>=90){
        average+=a;
        broj_na_clenovi++;
        }
    }

    double k=average/broj_na_clenovi;
    k += 0.001;
    printf("%.2f\n", k);
    return 0;
}