You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named (3R)-1-[5-chloro-6-ethyl-2-[(5-hydroxy-1,5-naphthyridin-5-ium-3-yl)sulfanyl]-7H-pyrrolo[2,3-d]pyrimidin-4-yl]pyrrolidin-3-amine by IUPAC nomenclature, provide its molecular formula.
user
C20H21ClN7OS+
assistant