class Parent{
	int x=100;
	void method(){
		System.out.println("Parent Method");
	}
}
class Child extends Parent{
	int x=200;
	void method(){
		System.out.println("Child Method");
	}
}

public class practice {

   public static void main(String[] args) throws InterruptedException{
	   Parent a = new Child();
	   Child b=null;

	   b=(Child)a; //down casting 형 변환해야함

	   Parent c=null;
	   Child d=new Child();
	   c=d; //up casting 형변환 생략가능

	   //-----------------------------------------//

	   Parent p = new Child();
	   Child q =new Child();
	   System.out.println("p.x = "+p.x);
	   p.method();
	   System.out.println("c.x = "+q.x);
	   c.method();
   }
}