You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule N-[(3,4-dimethyl-6-oxo-1H-pyridazin-5-yl)methyl]-4-[methyl(prop-2-enoyl)amino]benzamide into molecular formula.
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C18H20N4O3
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