You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Can you give the molecular formula of the molecule 1-[4-[[3-(4-chlorophenyl)-1,2,4-oxadiazol-5-yl]methyl]piperazin-1-yl]-2-(4-nitrophenyl)sulfanylethanone ?
user
C21H20ClN5O4S
assistant