You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named lithium;benzyl (2R,4S)-2-tert-butyl-6-methoxy-4-methyl-2,4-dihydropyrimidin-1-ide-3-carboxylate by IUPAC nomenclature, provide its molecular formula.
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C18H25LiN2O3
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