You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(3S)-3-(4-acetyl-3,5-dimethylpyrazol-1-yl)-N-(5-chloro-2-methoxyphenyl)butanamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C18H22ClN3O3
assistant