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 3-[3-[5-(5-cyanocyclohexa-2,4-dien-1-yl)-8,10b-dihydro-4aH-cyclohepta[b]indol-8-yl]carbazol-9-yl]benzonitrile .
user
C39H28N4
assistant