You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Can you give the molecular formula of the molecule N-[4-[(3aS,7aS)-1,3-dioxo-3a,4,5,6,7,7a-hexahydroisoindol-2-yl]-3-chlorophenyl]pyridine-2-carboxamide ?
user
C20H18ClN3O3
assistant