import java.util.Scanner;
public class media {
public static void main(String[]args) {
int n1, n2, n3, n4, n5, n6, n7, n8, n9, n10;
Scanner tec = new Scanner(System.in);
n1 = tec.nextInt();
n2 = tec.nextInt();
n3 = tec.nextInt();
n4 = tec.nextInt();
n5 = tec.nextInt();
n6 = tec.nextInt();
n7 = tec.nextInt();
n8 = tec.nextInt();
n9 = tec.nextInt();
n10 = tec.nextInt();
double media = (n1+n2+n3+n4+n5+n6+n7+n8+n9+n10)/10;
System.out.println(media);
}
}
