I'm trying to get the value of a subclass variable but don't know how to do it. It returns the super class attribute `0` because `d` is obviously of Type `Shape`. How could I access the correct value of the instance (`3`) without changing the class type of `d`? Is it possible?

```
public class Testclass {
    public static void main(String[] args) {
        Shape d = new Triangle(); 
        System.out.println(d.corners);;
    }
}

class Shape{
    int corners = 0;
}

class Triangle extends Shape{
    int corners = 3;
}

class Square extends Shape{
    int corners = 4;
}

```