You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(1S,2R,6S,7S,8R,10S)-4-[(Z)-(1-ethylindol-3-yl)methylideneamino]-4-azatetracyclo[5.3.2.02,6.08,10]dodec-11-ene-3,5-dione is the IUPAC name of a molecule. Please give its molecular formula.
user
C22H21N3O2
assistant