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-(3-fluorophenyl)-4-[4-[(2-methyl-1,3-thiazol-4-yl)methyl]piperazine-1-carbonyl]pyrrolidin-2-one .
user
C20H23FN4O2S
assistant