You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Convert the IUPAC name of a molecule 2-[[5-(3,4,5-trimethoxyphenyl)-1,3,4-oxadiazol-2-yl]sulfanylmethyl]pyrido[1,2-a]pyrimidin-4-one into molecular formula.
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C20H18N4O5S
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