You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Convert the IUPAC name of a molecule methyl (1R,3S,3aS,6aS)-3,5-diethyl-1-(4-methoxyphenyl)-4,6-dioxo-1,2,3a,6a-tetrahydropyrrolo[3,4-c]pyrrol-2-ium-3-carboxylate into molecular formula.
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C19H25N2O5+
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