public class Main {
    public static void main(String[] args) {
        Parent p = new Parent();
        Child c = new Child();
        Parent p2 = new Child();

        useIt(p);
        useIt(c);
        useIt(p2);
    }

    final static void useIt (Parent p){
        System.out.println("Parent");
    }

    final static void useIt (Child c){
        System.out.println("Child");
    }
}

class Parent { }
class Child extends Parent { }