class ClassOfStudents2 { 
    private final int N = 1000;
    private Student[] classMembers;
    private int number;

    // Constructor: make array, set number to zero.
    public ClassOfStudents2() {
	classMembers = new Student[N];
	number = 0;
    }

    public boolean insert(Student newStudent){
      if (number==N) 
          return false;
      int i;
      for(i = number++; i>0; i--) {
         int comparison = 
	 classMembers[i-1].surname.compareTo(newStudent.surname);
         if (comparison>0) 
             classMembers[i] = classMembers[i-1];
         else 
             break;
      }
      classMembers[i] = newStudent;
      return true;
    }

    public Student find(String surname) {
	int i = 0, j = number, mid;

	while (i < j) {
	    mid = (i+j)/2;    // NB: "/" takes integral part
	    int comparison = 
		classMembers[mid].surname.compareTo(surname);
	    if (comparison<0) {
		i = ++mid;
	    } else if (comparison>0) {
		j = mid;
	    } else {
		return classMembers[mid];
	    }
	}
	return null;
    }
}