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 (4R)-8-[3-chloro-5-(1-methyl-2,2-dioxo-3H-2,1-benzothiazol-5-yl)pyridin-4-yl]-4-methyl-1-oxa-3,8-diazaspiro[4.5]decan-2-one is given. What is its corresponding molecular formula?
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C21H23ClN4O4S
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