You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Please write the molecular formula of the molecule 3-(2,4-difluorophenyl)-2-ethyl-5-[4-(trifluoromethyl)phenyl]-3,6-dihydropyrimido[1,2-b]pyridazin-5-ium-4-one .
user
C22H17F5N3O+
assistant