You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name 3-chloro-4-[3-chloro-4-[(3,3-difluoroazetidine-1-carbothioyl)amino]phenoxy]-7-methoxyquinoline-6-carboxamide into its molecular formula.
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C21H16Cl2F2N4O3S
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