package com.codegym.task.task05.task0507;
import java.io.*;
/*
Arithmetic mean
*/
import java.util.Scanner;
public class Solution {
public static void main(String[] args) throws Exception {
//write your code
Scanner scanner = new Scanner(System.in);
double sum= 0;
while (true){
int number = 0;
if ( number !=-1)
sum= sum + number; number++;
number = scanner.nextInt();
System.out.println((sum)/number); break;}
}
}