why BufferedReader and Scanner is not working on the code editor its throwing the eroor But its working on my eclipse ide

package com.codegym.task.task04.task0412; /* Positive and negative numbers */ import java.io.BufferedReader; import java.io.InputStreamReader; public class Solution { public static void main(String[] args) throws Exception { //write your code here BufferedReader buffer = new BufferedReader(new InputStreamReader(System.in)); String num1 = buffer.readLine(); int num = Integer.parseInt(num1); if(num>0){ num = 2*num; System.out.println(num); } if(num<0){ num+=1; System.out.println(num); } if(num == 0){ System.out.println(num); } } }