You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(2S)-N-(3,4-dimethoxyphenyl)-2-[1-(4-fluorophenyl)-6-oxopyridazin-3-yl]oxypropanamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H20FN3O5
assistant