struct JSON {
  int value;
  std::vector<JSON> arr;
  bool isArray = false;
};

int parse_number(std::string &input, std::stack<JSON*> & stack, size_t &position) {
	char *end;
	char *start = input.c_str() + position;
	long result = std::strtol(start, &end, 10);
	if (errno == ERANGE || result > INT_MAX) {
		throw std::runtime_error("");
	}
	position += end - start;
	return result;
}

JSON parse_object(std::string &input, size_t &position) {
  switch(input[position]) {
  case('['):
     return parse_array(input, position);
     break;
  case('0'):
  case('1'):
  case('2'):
  case('3'):
  case('4'):
  case('5'):
  case('6'):
  case('7'):
  case('8'):
  case('9'):
     JSON result;
     result.value = parse_number(input, position);
     return result;
  default:
    throw std::runtime_error("muhahah");
  }
  ///unreachable
  return JSON();
}

JSON  parse_array(std::string &input, size_t &position) {
  JSON result;
  result.is_array = true;
  position++;
  for(;;) {
    result.arr.emplace_back(parse_object(input,position));
    switch(input[position]) {
	  case(','):
	    position++;
	    continue;
	  case(']'):
	    position++;
        return result;
      default:
        throw std::runtime_error();
    }
  }
  // unreachable
  return result;
}

JSON parse_json(std::string &input) {
	if (input.empty())
	  throw std::runtime_error("");
	size_t position = 0;
	auto result = parse_object(input, position);
	if (position != input.size())
	  throw std::runtime_error("");
	return result;
}