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 2-[7-(4-chlorophenyl)-2-oxo-1,3-dihydroimidazo[1,2-b]pyrazol-3-yl]-N-(2-ethoxyphenyl)acetamide is given. What is its corresponding molecular formula?
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C21H19ClN4O3
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