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-(4-aminophenyl)-6-[(2-methoxy-5-nitrophenyl)methyl]-3,5,7,8-tetrahydropyrido[4,3-d]pyrimidin-4-one into molecular formula.
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C21H21N5O4
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