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-[(1R,2S,3R)-3-methyl-2-[(1R)-3-(4-methylanilino)-1-nitro-2,3-dioxopropyl]-5-oxocyclopentyl]acetic acid into molecular formula.
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C18H20N2O7
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