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What is the molecular formula of the compound with this IUPAC name [(1R,2R,3R,4S)-4-acetyloxy-5-cyano-1,3,7-trihydroxy-3-methyl-6,11-dioxo-2,4-dihydro-1H-benzo[b]carbazol-2-yl] acetate ?
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C22H18N2O9
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