You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-[2-(2,3-dihydroindol-1-ylsulfonyl)ethyl]-2-(2-methylprop-2-enyl)guanidine;hydroiodide is the IUPAC name of a molecule. Please give its molecular formula.
user
C15H23IN4O2S
assistant