You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
3-[3-chloro-4-[(2,4-difluorophenyl)methoxy]-6-methyl-2-oxopyridin-1-yl]-4-methylbenzoate The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H15ClF2NO4-
assistant