You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[(4-chlorophenyl)methyl]-N-[2-(2-methyl-2,3-dihydroindol-1-yl)-2-oxoethyl]methanesulfonamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C19H21ClN2O3S
assistant