import java.util.HashSet;

class SetOps {

  public static void main(String[] args) {
    HashSet<Integer> setA = new HashSet<Integer>();
    setA.add(2);
    setA.add(3);
    setA.add(5);
    setA.add(8);
    System.out.println("setA => " + setA);
    HashSet<Integer> setB = new HashSet<Integer>();
    setB.add(1);
    setB.add(3);
    setB.add(7);
    setB.add(9);
    System.out.println("setB => " + setB);
    // Set union
    HashSet<Integer> unionSet = new HashSet<Integer>(setA);
    unionSet.addAll(setB);
    System.out.println("setA union setB =>" + unionSet);
    
    // Set intersection
    HashSet<Integer> intSet = new HashSet<Integer>(setA);
    intSet.retainAll(setB);
    System.out.println("setA intersect setB =>" + intSet);
    // Set difference (setA - setB)
    HashSet<Integer> diffSet = new HashSet<Integer>(setA);
    diffSet.removeAll(setB);
    System.out.println("setA - setB =>" + diffSet);
    
  }  // end main
} // end setOps