You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Provide the molecular formula for the IUPAC named substance 12-(ethoxymethyl)-9-ethyl-9,12-diazatetracyclo[9.7.0.02,7.013,18]octadeca-1(11),2,4,6,13,15,17-heptaen-10-one .
user
C21H22N2O2
assistant