interface Friend{
void chatWithCommonTopic();
}
class I implements Friend{
void chatWithCommonTopic(){
System.out.println("No common topic.");
}
}
class You implements Friend{
void chatWithCommonTopic(){
System.out.println("What topic?");
}
}
public class Post{
public static void main(String[] args){
You you=new You();
I i=new I();
you.chatWithCommonTopic();
i.chatWithCommonTopic();
}
}