You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
4,9'-dimethylspiro[4-azatricyclo[4.3.1.13,8]undecane-5,3'-benzo[f][1,4]benzoxazine] is the IUPAC name of a molecule. Please give its molecular formula.
user
C23H26N2O
assistant