You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule 3-[4-[2-(6-oxo-3-pyridin-3-ylpyridazin-1-yl)ethyl]piperazin-1-yl]pyridazine-4-carbonitrile into molecular formula.
user
C20H20N8O
assistant