You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule 3-[acetyl(ethyl)amino]-2-ethyl-N-(2-pyridin-2-ylethyl)imidazo[1,2-a]pyridine-6-carboxamide into molecular formula.
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C21H25N5O2
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