You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
3-[5,6-dibromo-2-[3-[5,6-dibromo-1-ethyl-3-(3-sulfopropyl)benzimidazol-3-ium-2-yl]prop-2-enylidene]-3-ethylbenzimidazol-1-yl]propane-1-sulfonic acid The above is the IUPAC name of a molecule. Write its molecular formula.
user
C27H31Br4N4O6S2+
assistant