You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-[1-(2,4-difluorophenyl)ethyl]-2-[[4-ethyl-5-(furan-2-yl)-1,2,4-triazol-3-yl]sulfanyl]acetamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H18F2N4O2S
assistant