You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
10-naphthalen-2-yl-2,3,4,4a,5,7-hexahydro-1H-pyrazino[1,2-a][1,3]benzodiazepin-6-one The above is the IUPAC name of a molecule. Write its molecular formula.
user
C22H21N3O
assistant