You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[2-(5-chloro-2,3-dihydro-1,4-benzodioxin-7-yl)ethyl]-1-(3-methoxyphenyl)guanidine The above is the IUPAC name of a molecule. Write its molecular formula.
user
C18H20ClN3O3
assistant