You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-(3,4-dihydro-2H-1,5-benzodioxepin-6-ylmethyl)-2-methyl-3-[1-(5-methylthiophen-2-yl)propan-2-yl]guanidine;hydroiodide is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H28IN3O2S
assistant