You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
4-[[[(1S,4aS,10aR)-1,4a-dimethyl-7-propan-2-yl-2,3,4,9,10,10a-hexahydrophenanthren-1-yl]methylazaniumyl]methyl]benzoate is the IUPAC name of a molecule. Please give its molecular formula.
user
C28H37NO2
assistant