You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(2S)-3-(4-fluorophenyl)-N-(furan-2-ylmethyl)-2-[3-(hydroxymethyl)pyridin-1-ium-1-yl]-3-oxopropanethioamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C20H18FN2O3S+
assistant