You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named (5Z)-3-[4-(2-chlorophenothiazin-10-yl)-4-oxobutyl]-5-[(4-methoxyphenyl)methylidene]-2-sulfanylidene-1,3-thiazolidin-4-one by IUPAC nomenclature, provide its molecular formula.
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C27H21ClN2O3S3
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