You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
3-[(3S)-3-[3-(3-chloro-5-fluorophenyl)propanoyl]-3-hydroxy-2-oxopyrrolidin-1-yl]-4-fluorobenzamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H17ClF2N2O4
assistant