You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(Z)-2-(1H-benzimidazol-2-yl)-3-(3,5-dichloro-4-ethoxyphenyl)prop-2-enenitrile is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H13Cl2N3O
assistant