A large downtown hotel consists of twenty-four levels. Twenty-two of the levels lie above ground and two of the levels are reserved for underground parking. Above ground levels are called "floors," however, the first floor is also referred to as the "ground level." The first level below ground level is Parking A, and the second level below ground level is labeled Parking B. Use the provided horizontal number line to help you answer the following questions.

If each above ground level floor corresponds with its floor number on the number line, what number on the number line represents Parking A? [Type your answer as a number.]