You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 2-[(6-chloro-1H-benzimidazol-2-yl)sulfanyl]-N-(2-cyanoethyl)-N-(3,5-dimethylphenyl)acetamide by IUPAC nomenclature, provide its molecular formula.
user
C20H19ClN4OS
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