You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(4Z)-1-butyl-4-[(4-ethoxyphenyl)-hydroxymethylidene]-5-(4-propan-2-ylphenyl)pyrrolidine-2,3-dione is the IUPAC name of a molecule. Please give its molecular formula.
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C26H31NO4
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