You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule N-[[1-(3-methylphenyl)pyrazol-4-yl]methyl]-6-oxo-2-pyridin-3-yl-1H-pyrimidine-5-carboxamide into molecular formula.
user
C21H18N6O2
assistant