You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name N-[2-chloro-5-(trifluoromethyl)phenyl]-2-[3-methyl-4-(4-methylphenyl)piperazin-1-yl]acetamide into its molecular formula.
user
C21H23ClF3N3O
assistant