public class P214_Inheritance {

	public static void main(String[] args) {
		A a = new B();
		System.out.println(a.f());
		B b = (B) a;
		System.out.println(b.f());
	}

	private static class A {

		int a = 1, b = 2;

		int f() {
			return a + b;
		}

	}

	private static class B extends A {

		int c = 3;

		@Override
		int f() {
			return super.f() + c;
		}

	}

}