You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
7-[(4-fluorophenyl)methyl]-1,3-dimethyl-8-(pyridin-3-ylmethylamino)purine-2,6-dione The above is the IUPAC name of a molecule. Write its molecular formula.
user
C20H19FN6O2
assistant