You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
17-bromo-3,10-diazapentacyclo[10.7.1.02,10.04,9.016,20]icosa-1(20),2,4,6,8,12,14,16,18-nonaen-11-one The above is the IUPAC name of a molecule. Write its molecular formula.
user
C18H9BrN2O
assistant