You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule (2S)-N-(3-chloro-4-methoxyphenyl)-2-methyl-3-[(4-oxo-3,5-dihydro-2H-1,5-benzothiazepin-7-yl)sulfonyl]propanamide into molecular formula.
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C20H21ClN2O5S2
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