You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Under IUPAC nomenclature, a molecule named 4-[(9-cyclobutyl-5-methyl-6-oxo-7,8-dihydropyrimido[4,5-b][1,4]diazepin-3-ium-2-yl)amino]-3-methoxybenzamide is given. What is its corresponding molecular formula?
user
C20H25N6O3+
assistant