You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(6S)-5-methyl-7-phenyl-6-pyridin-3-yl-2,3,4,6-tetrahydropyrrolo[3,4-e][1,4]diazepin-8-one The above is the IUPAC name of a molecule. Write its molecular formula.
user
C19H18N4O
assistant