public boolean check() throws IOException {
        for (Map.Entry<String, String> node : old.entrySet()) {
            int zeroByte = Math.abs(node.getKey().getBytes(StandardCharsets.UTF_8)[0]);
            if (!((zeroByte % 16 == direcotryNumber) && ((zeroByte / 16) % 16 == fileNumber))) {
                throw new IOException("Wrong file format key[0] =  " + String.valueOf(zeroByte)
                        + " in file " + fileName);
            }
            try {
                provider.deserialize(table, node.getValue());
            } catch (ParseException e) {
                throw new IOException("Invalid file format! (parse exception error!)");
            }
        }
        return true;
    }