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 6-[2-[(2S)-2-methylazetidin-1-yl]-6,7-dihydro-5H-cyclopenta[d]pyrimidin-4-yl]-2H-isoquinolin-3-one .
user
C20H20N4O
assistant