You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name N-[4-[7-(3-fluoro-4-methoxyphenyl)-1,3-dimethyl-2,6-dioxopurin-8-yl]phenyl]acetamide into its molecular formula.
user
C22H20FN5O4
assistant