You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[1-(2,3-dimethylphenyl)-3-phenylbut-3-enyl]-4,5-dihydro-1,3-thiazol-2-amine is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H24N2S
assistant