/** Class for a student. */
public class Student implements Person {
  String id;
  String name;
  int age;
  /** Constructor. */
  public Student (String i, String n, int a) {
    id = i;
    name = n;
    age = a;
  }

  /** Number of hours spent studying weekly */
  protected int studyHours() {
    return age/2;	// guessing it is proportional to the age
  }

  //** ID of the student. */
  public String getID () {
    return id;
  }

  // The next three methods are for implementing the Person interface.
  public String getName() {
    return name;
  }
  public int getAge() {
    return age;
  }
  public boolean equalTo (Person other) {
    Student otherStudent = (Student) other;	// cast Person to Student
    return (id.equals (otherStudent.getID()));	// compare IDs
  }
}