You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[4-(1,3-dimethylbenzimidazol-3-ium-2-yl)butyl]-1,3-dimethylbenzimidazol-3-ium;diiodide;hydroiodide is the IUPAC name of a molecule. Please give its molecular formula.
user
C22H29I3N4
assistant