package com.javarush.task.task05.task0507;
import java.io.BufferedReader;
import java.io.InputStreamReader;
public class Solution {
public static void main(String[] args) throws Exception {
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
double y = 0;
double z = 0;
while (true) {
double x = Integer.parseInt(reader.readLine());
y = y + x;
z = z + 1;
if (x == -1)
break;}
double i = y/z;
System.out.println(i);
}
}
package com.javarush.task.task05.task0507;
import java.io.BufferedReader;
import java.io.InputStreamReader;
public class Solution {
public static void main(String[] args) throws Exception {
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
double y = 0;
double z = 0;
while (true) {
double x = Integer.parseInt(reader.readLine());
y = y + x;
z = z + 1;
if (x == -1)
break;}
double i = y/(z-1);
System.out.println(i);
}
}