You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Convert the IUPAC name of a molecule (E)-2-cyano-3-[1-(2,5-dichlorophenyl)-2,5-dimethylpyrrol-3-yl]-N-[[(2R)-oxolan-2-yl]methyl]prop-2-enamide into molecular formula.
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C21H21Cl2N3O2
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