import java.util.*;
import java.util.stream.*;

class Main {
	public static void main(String[] args) {
		Set<Integer> foo = new HashSet<>(Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8));
		System.out.println(foo);
		Set<Integer> bar = foo.stream()
		  .filter(i -> i % 2 == 0)
		  .peek(foo::remove)
		  .collect(Collectors.toSet());
		System.out.println(foo);
		System.out.println(bar);
	}
}