static void union(int s, int t){
        List<Set<Integer>> hack = new LinkedList<>();
        for (Set<Integer> e : list) {
            Set<Integer> union = new HashSet<>();
            if(e.contains(s) && !e.contains(t)) {
                union.addAll(e);
                union.add(t);
                e.clear();
            }else if(e.contains(t) && !e.contains(s)) {
                union.addAll(e);
                union.add(s);
                e.clear();
            }
            hack.add(union);
        }
        list.addAll(hack);
    }