You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
hydroxy-[5-[6-(1-hydroxypyridin-1-ium-2-yl)pyridin-2-yl]hexa-2,4-dienyl]azanium is the IUPAC name of a molecule. Please give its molecular formula.
user
C16H19N3O2+2
assistant