You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
[(1S,9S)-8-oxa-2,3,4,12-tetrazatricyclo[7.4.0.02,6]trideca-3,5-dien-12-yl]-(1-phenylcyclohexyl)methanone The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H26N4O2
assistant