You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(2R)-1-(5-chlorothiophene-2-carbonyl)-N-[(1S)-1-(5-fluoro-2-methoxyphenyl)ethyl]pyrrolidine-2-carboxamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C19H20ClFN2O3S
assistant