You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(2S,3R)-2-ethyl-N-[2-methyl-3-[(4R)-4-(2-methylpropylamino)oxolan-2-yl]propyl]oxolan-3-amine is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H36N2O2
assistant