You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 1-(2-ethylpiperidin-1-yl)-2-[(6-methoxy-1H-benzimidazol-2-yl)sulfanyl]propan-1-one by IUPAC nomenclature, provide its molecular formula.
user
C18H25N3O2S
assistant