You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule (4aR)-1-propyl-2,3,4,4a,5,7,9,9a-octahydropyrrolo[3,4-g]quinoline;(Z)-but-2-enedioic acid into molecular formula.
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C18H26N2O4
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