You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Please write the molecular formula of the molecule (8R,8aS)-2-acetyl-8-(2-chlorophenyl)-6-imino-3,5,8,8a-tetrahydro-1H-isoquinoline-5,7,7-tricarbonitrile .
user
C20H16ClN5O
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