You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 2-ethyl-1-[2-(2-hydroxyethoxy)ethylamino]-3-methyl-5H-pyrido[1,2-a]benzimidazol-10-ium-4-carbonitrile by IUPAC nomenclature, provide its molecular formula.
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C19H23N4O2+
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