You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-(2-bicyclo[2.2.1]heptanyl)-2-(4-ethoxybutyl)-3-[2-(furan-2-yl)ethyl]guanidine is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H33N3O2
assistant