You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Provide the molecular formula for the IUPAC named substance 1-[2-(3-fluorophenyl)piperazin-1-yl]-2-[(2,2,2-trifluoro-1-phenylethyl)amino]ethanone .
user
C20H21F4N3O
assistant