public function convertFromNegative($input)
    {
        if (strpos('/*', $input[0]) !== false) {
            $input = substr($input, 1);
        }

        $input = strtr($input, static::NEGATIVE_CHARS, static::POSITIVE_CHARS);

        $res = $this->convertFromPositive($input);

        if (preg_match('/^0+$/', $res)) {
            return $res;
        }

        return '-' . $res;
    }