How musical notes are there?

There are twelve distinct musical notes: A, A#/Bb, B, C, C#/Db, D, D#/Eb, E, F, F#/Gb, G, G#/Ab.

1. A

2. A#/Bb

3. B

4. C

5. C#/Db

6. D

7. D#/Eb

8. E

9. F

10. F#/Gb

11. G

12. G#/Ab