import java.util.*;

public class FindDuplicateStudents{
   
  public static void main(String args[]) {
    Collection<Student> students = new ArrayList<>();
    students.add(new Student("John", "Smith"));
    students.add(new Student("Stanley", "Peters"));
    students.add(new Student("Edgar", "Bloch"));
    students.add(new Student("Suzan", "Miles"));
    students.add(new Student("Mary", "Poppins"));
    students.add(new Student("John", "Smith"));
    students.add(new Student("Stanley", "Peters"));
        
    Collection <Student> uniques = new HashSet<Student>();
    Collection <Student> dups = new HashSet<Student>();
    
    for(Student st : students) {
      if(uniques.contains(st))
        dups.add(st);
      else
        uniques.add(st);
    }
    
    uniques.removeAll(dups);
    System.out.println("-- Uniques --");
    print(uniques);
    System.out.println("-- Dups --");
    print(dups);
  }
  
  public static void print(Collection<Student> collection) {
    Iterator<Student> it = collection.iterator();
    while(it.hasNext())
      System.out.println(it.next());
  }
}