You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(4R)-4-[4-[(2-fluorophenyl)methoxy]-3-methoxyphenyl]-3-methyl-2,4,5,7-tetrahydropyrazolo[3,4-b]pyridin-6-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H20FN3O3
assistant