You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
ethyl 4-[5-(hydroxymethyl)-1-[[2-(trifluoromethyl)phenyl]methyl]imidazol-2-yl]sulfanylbutanoate The above is the IUPAC name of a molecule. Write its molecular formula.
user
C18H21F3N2O3S
assistant