class Student implements Comparable<Student> {
  String name;
  private Integer age; 
  Student(String name, Integer age) {
    this.name = name;
    this.age = age; 
  }
  public int compareTo(Student other) {
    return this.age - other.age;  
  }
  public String toString() {
    return name + "/" + age; 
  }
}