You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-(4-methoxyphenyl)-3-[(5-oxo-3-phenyl-2H-oxadiazol-3-ium-4-yl)sulfanyl]propanamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C18H18N3O4S+
assistant