You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
8-[2-chloro-3-[2-chloro-5-fluoro-3-(5-formyl-6-methoxypyridin-2-yl)phenyl]phenyl]-4-oxopyrido[1,2-a]pyrimidine-3-carbaldehyde is the IUPAC name of a molecule. Please give its molecular formula.
user
C28H16Cl2FN3O4
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