You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Please write the molecular formula of the molecule N-methyl-N-[(4-methylphenyl)methyl]-2-[4-[5-(trifluoromethyl)pyridin-1-ium-2-yl]piperazin-1-ium-1-yl]acetamide .
user
C21H27F3N4O+2
assistant