You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-(2,3-dihydro-1H-inden-5-yl)-2-[2-methyl-2-(3-methylpiperidin-1-yl)propyl]guanidine;hydroiodide is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H33IN4
assistant