You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1,2-dimethyl-3-[(4-methylsulfanyloxan-4-yl)methyl]-1-[(4-methylsulfanylphenyl)methyl]guanidine is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H29N3OS2
assistant