You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Under IUPAC nomenclature, a molecule named N-[6-(6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl)pyridazin-3-yl]cyclobutanecarboxamide is given. What is its corresponding molecular formula?
user
C20H24N4O3
assistant