You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
What is the molecular formula of the compound with this IUPAC name (4S)-4-[[4-[1-(4-methoxyphenyl)pyrazol-4-yl]pyrimidin-2-yl]amino]-1-methylpyrrolidin-2-one ?
user
C19H20N6O2
assistant