You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-(3-ethylsulfonylpyridin-2-yl)-3,4-dimethyl-6-(trifluoromethyl)imidazo[4,5-b]pyridin-4-ium The above is the IUPAC name of a molecule. Write its molecular formula.
user
C16H16F3N4O2S+
assistant