You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule 1-[(7R)-7-methyl-6-(1H-pyrrolo[2,3-b]pyridin-4-yl)-7,8-dihydro-5H-pyrido[4,3-d]pyrimidin-4-yl]piperidine-3-carbonitrile into molecular formula.
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C21H23N7
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