You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name (2R)-N-(4-acetylphenyl)-2-[4,5-dimethyl-1-(2-methylpropyl)imidazol-2-yl]sulfanylpropanamide into its molecular formula.
user
C20H27N3O2S
assistant