You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name N-(4,4-difluorocyclohexyl)-1-(1H-pyridin-4-ylidene)-2,3-dihydroimidazo[1,5-a]pyridin-4-ium-3-carboxamide into its molecular formula.
user
C19H21F2N4O+
assistant