You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
methyl 2-cyano-6-[4-(6-methoxypyridin-3-yl)oxypiperidin-1-yl]-5-methylpyridine-3-carboxylate The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H22N4O4
assistant