You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Under IUPAC nomenclature, a molecule named [1-(4-fluoroanilino)-1-oxobutan-2-yl] 1-oxo-2,3-dihydropyrrolo[2,1-b][1,3]benzothiazole-3a-carboxylate is given. What is its corresponding molecular formula?
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C21H19FN2O4S
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