You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Provide the molecular formula for the IUPAC named substance 1,3-dimethyl-5-prop-2-enylsulfanyl-4aH-pyrido[2,3-d]pyrimidin-1-ium-2,4-dione .
user
C12H14N3O2S+
assistant