You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(3R)-1,3-dimethyl-N-[(1R,2S,4R)-7-oxabicyclo[2.2.1]heptan-2-yl]-3,5-dihydro-2H-1,4-benzodiazepine-4-carboxamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H25N3O2
assistant