You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule 2-[3-[(E)-(3-benzamido-4-oxo-2-sulfanylidene-1,3-thiazolidin-5-ylidene)methyl]phenoxy]butanoic acid into molecular formula.
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C21H18N2O5S2
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