You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Under IUPAC nomenclature, a molecule named (2R)-3-methyl-2-[3-(2-oxo-3-propylbenzimidazol-1-yl)propanoylamino]butanoic acid is given. What is its corresponding molecular formula?
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C18H25N3O4
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