You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named (1R,9S,10R)-4-methoxy-17-methyl-17-azatetracyclo[7.5.3.01,10.02,7]heptadeca-2(7),3,5-trien-8-one by IUPAC nomenclature, provide its molecular formula.
user
C18H23NO2
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