You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named (4S,4aR,5S,8aR)-3,5,8-trimethyl-4-[(E)-2-phenylethenyl]-1,4,4a,5,6,8a-hexahydropyrimido[4,5-d]pyrimidine-2,7-dione by IUPAC nomenclature, provide its molecular formula.
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C17H22N4O2
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