Set<String> obj = new HashSet<>();
        
        for (int i = 0; i < t; i++) {
            
            String strKey = pair_left[i] +" "+ pair_right[i];
            String strInvertKey = pair_right[i] +" "+ pair_left[i];
            
            if(!obj.contains(strKey) && !obj.contains(strInvertKey)){
                obj.add(strKey);
            }
            
            System.out.println(obj.size());
        }