interface customer
{
    int a= 20; /* that is why its final because one value  is assinged it becomes final*/
    
    void purchase();
}
class Raju implements customer
{
    @Override
    public void purchase()
    {
        System.out.println("raj needs "+a+"kg");
    }
}
class Check
{
    public static void main(String[] args)
    {
        customer r= new Raju();
        r.purchase();
    }
}