You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[4-(3-chloro-4-fluoroanilino)quinazolin-6-yl]-6,7-dihydropyrano[3,4-c]pyrrol-4-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H14ClFN4O2
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