import java.util.Scanner;

public class Exam {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        int n = Integer.parseInt(scanner.nextLine());
        int count = 0;
        int exelent = 0;
        int good5 = 0;
        int between = 0;

        int fail = 0;
        double exelent1 = 0;
        double good1 = 0;
        double between1 = 0;
        double fail1 = 0;
        double avareg = 0;

        for (int i = 0; i <= n ; i++) {
            double grades = Double.parseDouble(scanner.nextLine());
            avareg += grades;

            if(grades > 2.00 & grades < 2.99){
                fail++;
                fail1 += grades;
            }else if (grades > 3.00 && grades < 3.99){
                between++;
                between1 += grades;
            }else if (grades > 4.00 && grades < 4.99){
                good5++;
                good1 += grades;
            }else if (grades >= 5.00){
                exelent++;
                exelent1 += grades;
            }
        }
        double percentexelent = exelent1 * 1.0 / exelent * 100;
        double percentgood = good1 / good5 * 100;
        double percentbetween = between1 / between * 100;
        double percentfail = fail1 / fail * 100;
        double percentAvarege = avareg * 1.0 / count * 100;

        System.out.printf("%.2f", percentAvarege);

    }
}