You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Can you give the molecular formula of the molecule 9-chloro-8-(4,6-diethyl-2-methylpyrimidin-5-yl)-1,2,3,4-tetrahydropyrimido[1,2-a]benzimidazole-6-carbaldehyde ?
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C20H22ClN5O
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