You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-benzyl-2-[(4-ethyl-5-thiophen-2-yl-1,2,4-triazol-3-yl)sulfanyl]propanamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H20N4OS2
assistant