You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
16-amino-3-methyl-11-azapentacyclo[11.8.0.02,11.04,9.015,20]henicosa-1,4,6,8,12,15(20),16,18-octaene-14,21-dione is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H16N2O2
assistant