Can anyone tell me where I made a mistake?
package pl.codegym.task.task04.task0412;
/*
Liczby dodatnie i ujemne
*/
import java.io.*;
public class Solution {
public static void main(int[] args) throws Exception {
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
String vs = reader.readLine();
int a = Integer.parseInt(vs);
if (a > 0){
a = a*2;
System.out.println(a);
}
else if (a < 0){
a = a+1;
System.out.println(a);
}
else if (a == 0){
System.out.println(a);
}
}
}