You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Provide the molecular formula for the IUPAC named substance (3R,3aS)-3-methyl-5-(4-methylphenyl)-2-phenyl-1,3,3a,6a-tetrahydropyrrolo[3,4-c]pyrrole-4,6-dione .
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C20H20N2O2
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