You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
3-ethyl-2-[[1-(2-methoxyethyl)cyclopentyl]methyl]-1-methyl-1-(oxolan-3-ylmethyl)guanidine is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H35N3O2
assistant