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 3-[3-(cyclobutylamino)propyl]-1-pyrrolidin-2-yl-6,7,8,9-tetrahydro-4H-pyrazolo[3,4-c]isoquinolin-5-one .
user
C21H31N5O
assistant