You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name (3R)-3-methyl-1-[(4-methylphenyl)methyl]-4-(1H-pyrrolo[2,3-b]pyridin-6-yl)piperazin-2-one into its molecular formula.
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C20H22N4O
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