import java.util.Scanner;
public class Main {
public static void main(String[] args) {
double n;
int a=0;
int b;
double c;
Scanner in=new Scanner(System.in);
n=in.nextInt();
for(int i=1;i<=n;i++) {
b=in.nextInt();
if(b<60) {
a=a+1;
}
}
c=a/n;
System.out.println(String.format("%.2f",c));
}
}