You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named [phenyl(pyridin-2-yl)methyl] 2-(3-benzyl-7-ethyl-2,6-dioxopurin-1-yl)acetate by IUPAC nomenclature, provide its molecular formula.
user
C28H25N5O4
assistant