You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
18-bromo-6-ethenyl-4-methylidene-3,11-diazapentacyclo[11.7.1.02,11.05,10.017,21]henicosa-1(21),2,5,7,9,13,15,17,19-nonaen-12-one The above is the IUPAC name of a molecule. Write its molecular formula.
user
C22H13BrN2O
assistant