Inheritance Basic

class A{
    int i,j;
    void showij(){
        System.out.println("i & j: " + i +" "+ j);
    }
}
class B extends A{
    int k;
    void showk(){
        System.out.println("k is: " + k);
    }
    void sum(){
        System.out.println("The sum of i, j and k is: " + (i+j+k));
    }
}
public class Main{
    public static void main(String args[]){
        A supob = new A();
        B subob = new B();
       supob.i=5;
       supob.j=7;
       supob.showij();
       subob.i=12;
       subob.j=8;
       subob.k=10;
       subob.showk();
       subob.sum();
    }
}