Why my code do not pass ? :( I've done similar exercise in IntelliJ and it return correct result. Like below: class cwiczenie1 { public static void main(String[] args) throws Exception { // ArrayList HashSet<Integer> set1 = new HashSet<>(); set1.add(2); set1.add(3); set1.add(14); set1.add(6); set1.add(11); set1.add(13); System.out.println(set1); System.out.println(utworzSet()); System.out.println(usunLiczbyWiekszeNiz10(utworzSet())); } public static HashSet<Integer> utworzSet() { HashSet<Integer> set = new HashSet<>(); set.add(1); set.add(2); set.add(3); set.add(4); set.add(12); return set; } public static HashSet<Integer> usunLiczbyWiekszeNiz10(HashSet<Integer> set) { HashSet<Integer> set2 = new HashSet<>(); for (Integer number : set) { if (number < 10) set2.add(number); } return set2; } }