You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(2S,4S)-N-[[4-(2-cyanophenyl)phenyl]methyl]-4-methoxy-1-methylpyrrolidine-2-carboxamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H23N3O2
assistant