You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
7-bromo-3,10-diphenyl-3,10-diazapentacyclo[11.7.1.02,11.04,9.017,21]henicosa-1(21),2(11),4(9),5,7,12,14,16,18-nonaene is the IUPAC name of a molecule. Please give its molecular formula.
user
C31H21BrN2
assistant