You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-phenylethyl (4S)-4-(2,4-dichlorophenyl)-6-methyl-2-oxo-3,4-dihydro-1H-pyridine-5-carboxylate is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H19Cl2NO3
assistant