You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(1S,2S,5R,9S)-2-(1-methylpiperidin-1-ium-1-yl)bicyclo[3.3.1]nonan-9-ol The above is the IUPAC name of a molecule. Write its molecular formula.
user
C15H28NO+
assistant