import java.util.*;


class Person {
  String name;
}

class Teacher extends Person {
  String grade;
}

class Census {
    public static void register(List<? extends Person> people) {
       for (Person p: people) {
          System.out.println(p.name);
       }
       // people.add(new Person());   // you can't do that
    }
}

class G14 {
  public static void main( String[] args ){
    List<Teacher> record = new LinkedList<Teacher>();
    // fill teachers' record
    Census.register(record);
  }
}