package p;
import java.util.ArrayList;
import java.util.List;
interface I {
public List<String> getList();
}
class A implements I {
public List<String> getList() {
List<String> list= new ArrayList<String>();
list.add("X");
return list;
}
}
class B extends A {
public List<String> getList() {
return null;
}
}