You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
6-[(1S)-1-cyano-2-(3,4-dimethylphenyl)-2-oxoethyl]-N,N-diethylpyridine-3-sulfonamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H23N3O3S
assistant