You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-[4-(2-oxo-1,3-dihydrobenzimidazol-5-yl)butanoyl]pyrrolidine-3-carboxylic acid;hydrochloride is the IUPAC name of a molecule. Please give its molecular formula.
user
C16H20ClN3O4
assistant