You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named methyl (1R,3aS,6aR)-3-(4-methylphenyl)-4,6-dioxo-5-phenyl-3a,6a-dihydro-1H-pyrrolo[3,4-c]pyrrole-1-carboxylate by IUPAC nomenclature, provide its molecular formula.
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C21H18N2O4
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