You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Under IUPAC nomenclature, a molecule named (5E)-3-ethyl-5-[[2-(4-ethylphenoxy)-9-methyl-4-oxopyrido[1,2-a]pyrimidin-3-yl]methylidene]-2-sulfanylidene-1,3-thiazolidin-4-one is given. What is its corresponding molecular formula?
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C23H21N3O3S2
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