You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
9-[(3,4-difluorophenyl)methoxy]-3-[1-(2-methoxyphenyl)-5-methylpyrazol-3-yl]-2-methylpyrido[1,2-a]pyrimidin-4-one The above is the IUPAC name of a molecule. Write its molecular formula.
user
C27H22F2N4O3
assistant