You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
3-[3-[4-(4-acetylphenyl)piperazin-1-yl]-3-oxopropyl]-5-thiophen-2-yl-1,3,4-oxadiazol-2-one The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H22N4O4S
assistant