You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[(2S)-4-[4-(2-thiophen-2-yl-1,3-thiazol-4-yl)phenyl]butan-2-yl]acetamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C19H20N2OS2
assistant