Map<String, ArrayList<ArrayList<String>>> datasOfClass(ArrayList<ArrayList<String>> datas){
        Map<String, ArrayList<ArrayList<String>>> map = new HashMap<String, ArrayList<ArrayList<String>>>();
        ArrayList<String> t;
        String c;
        for (ArrayList<String> data : datas) {
            t = data;
            c = t.get(t.size() - 1);
            if (map.containsKey(c)) {
                map.get(c).add(t);
            } else {
                ArrayList<ArrayList<String>> nt = new ArrayList<ArrayList<String>>();
                nt.add(t);
                map.put(c, nt);
            }
        }
        return map;
    }