interface X
{
    void frontened();
    void backened();
}
abstract class D implements X
{
    @Override
    public void frontened()
    {
        System.out.println("BY JAVA");
    }
}
class W extends D
{
    @Override
    public void backened()
    {
        System.out.println("BY HTml and css ");
    }
}
class V
{
    public static void main(String[] args)
    {
        W r= new W();
        r.frontened();
        r.backened();
    }
    
}