You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
4-fluoro-N-[1-[4-(3-methoxyphenyl)piperazin-1-yl]-3-methyl-1-oxobutan-2-yl]benzamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C23H28FN3O3
assistant