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 1-[(2S)-2-(6-acetyl-7,8-dihydro-5H-pyrido[4,3-d]pyrimidin-2-yl)pyrrolidin-1-yl]-2-cyclohexylethanone .
user
C21H30N4O2
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