You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[2-[4-(3-chlorophenyl)piperazin-1-yl]-2-oxoethyl]-3-(2-oxopyridin-1-yl)propanamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H23ClN4O3
assistant