You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
What is the molecular formula of the compound with this IUPAC name 2-chloro-4-fluoro-N-[5-(3-fluoro-4-oxopyrido[1,2-a]pyrimidin-7-yl)-2-methoxypyridin-3-yl]benzenesulfonamide ?
user
C20H13ClF2N4O4S
assistant