abstract class A {
	abstract void callme();
	void callmetoo(){
		System.out.println("This is a concrete method.");
	}
}

class B extends A {
	void callme(){
		System.out.println("B's implementation of callme.");
	}
}

public class AbstractDemo {
	public static void mian(String args[]){
		B b=new B();
		b.callme();
		b.callmetoo();
	}
}