You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
9-[2,5-di(carbazol-9-yl)-6-(3,4-dihydrocarbazol-9-yl)-4-(5,6-diphenylpyrazin-2-yl)pyridin-3-yl]carbazole The above is the IUPAC name of a molecule. Write its molecular formula.
user
C69H45N7
assistant