You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule (4-methoxyphenyl)methyl N-[(2R,3R)-2-[(4-methoxyphenyl)methylsulfanylmethyl]-4-oxoazetidin-3-yl]carbamate into molecular formula.
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C21H24N2O5S
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