import java.util.*;

class Student {
    private String name;
    private String number;
    Student(String name, String number) {
        this.name = name;
        this.number = number;
    }

    @Override
    public String toString()  {
        return String.format("(%s, %s)", name, number);
    }
}

public class Students {
    public static void main(String[] args) {
        Set students = new HashSet();
        students.add(new Student("Bob", "B83"));
        students.add(new Student("Monica", "B84"));
        students.add(new Student("Bob", "B83"));
        System.out.println(students);
    }
}