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-[4-(2-methylphenyl)piperazin-1-yl]-2-(1-methylpyrrolo[2,3-b]pyridin-3-yl)ethanone .
user
C21H24N4O
assistant