You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
ethyl (1S,4S,5R,9S,10S,13S,14S,18S)-5,9,13-trimethyl-16-oxa-15-azapentacyclo[11.5.1.01,10.04,9.014,18]nonadecane-5-carboxylate is the IUPAC name of a molecule. Please give its molecular formula.
user
C23H37NO3
assistant