You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named (1S)-1-[3-chloro-2-(3,4-difluorophenyl)-7,8-dihydro-5H-1,6-naphthyridin-6-yl]-1-(2-chloro-4-nitroimidazol-1-yl)-2-methylpropan-2-ol by IUPAC nomenclature, provide its molecular formula.
user
C21H19Cl2F2N5O3
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