debug the following code and please explain

Question

public class Program {
public static void main(String[] args) {
int a = -66;
Math.abs (a);
System.out.println(a);

}
}

Answer 1

public class Program {
public static void main(String[] args) {
int a = -66;
System.out.println(Math.abs(a));
}
}

or if you want to change the value of a

public class Program {
public static void main(String[] args) {
int a = -66;
a = Math.abs(a);
System.out.println(a);
}
}