You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule (7S)-7-cyclopropyl-N-[5-methoxy-6-(4-methylimidazol-1-yl)pyridin-3-yl]-8-methyl-6,7-dihydropyrimido[5,4-b][1,4]oxazin-2-amine into molecular formula.
user
C20H23N7O2
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