You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(3S)-5-phenyl-9-piperazin-1-yl-3-propan-2-yl-1,3-dihydro-1,4-benzodiazepin-2-one The above is the IUPAC name of a molecule. Write its molecular formula.
user
C22H26N4O
assistant