You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule N-[2-[2-(4-chlorophenyl)ethylcarbamoyl]phenyl]-6-methyl-2,3-dihydro-1,4-oxathiine-5-carboxamide into molecular formula.
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C21H21ClN2O3S
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