You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Translate the chemical IUPAC name (4R,9aS)-4-methyl-7,8,9,9a-tetrahydro-1H-pyrrolo[2,1-c][1,4]thiazepine-3,5-dione into its molecular formula.
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C9H13NO2S
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