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 12-(9,9'-spirobi[fluorene]-2-yl)spiro[12-azapentacyclo[15.2.1.05,19.06,11.013,18]icosa-1,3,5(19),6,8,10,13,15,17-nonaene-20,9'-fluorene] .
user
C56H33N
assistant