You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name [(2S)-3-methyl-2-[3-(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-1-ium-1-yl]butyl] methanesulfonate into its molecular formula.
user
C18H29N2O3S+
assistant