You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-[4-(3-ethyl-1,2,4-thiadiazol-5-yl)-1,4-diazepan-1-yl]-2-(3-fluorophenyl)ethanone is the IUPAC name of a molecule. Please give its molecular formula.
user
C17H21FN4OS
assistant