You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
methyl 12-(1-hydroxyethyl)-14-oxido-8-aza-14-azoniapentacyclo[9.5.2.01,9.02,7.014,17]octadeca-2,4,6,9-tetraene-10-carboxylate The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H24N2O4
assistant