You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule 5-[4-(3H-benzimidazole-5-carbonyl)piperazin-1-yl]-4-chloro-1-benzofuran-2-carboxylic acid into molecular formula.
user
C21H17ClN4O4
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