You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[2-[2-(4-chlorophenyl)ethylamino]-2-oxoethyl]-4-(2-oxopyrrolidin-1-yl)benzamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H22ClN3O3
assistant