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 4-[(8R)-8-ethyl-5-oxo-4-propyl-8,9-dihydro-7H-imidazo[2,1-f]purin-2-yl]bicyclo[2.2.2]octane-1-carboxylic acid is given. What is its corresponding molecular formula?
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C21H29N5O3
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