It's saying the "BufferedReader" symbol dosen't exist or it cant recognise it.
package com.codegym.task.task05.task0507;
/*
Arithmetic mean
*/
public class Solution {
public static void main(String[] args) throws Exception {
//write your code here
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
int sum = 0;
int j = 0;
double poo = 0;
do
{
String s = reader.readLine();
n = Integer.valueOf(s);
sum = sum + n;
j++;
}while( n != -1);
poo = sum / j;
System.out.println(poo);
}
}