Inherit.java

class A {
    private int a;

    // private int b;
    int b;

    // private void aa() {
    //     a++;
    // }

    void aa() {
        a++;
    }
}

class B extends A {
    void bb() {
        b++;
    }
}

public class Inherit {
    public static void main(String[] args) {
        B b = new B();
        b.aa();
        A a = b;
        a.aa();
    }
}