You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Under IUPAC nomenclature, a molecule named 2-(2H-benzotriazole-5-carbonyl)-3-[(2,6-dichloropyridin-4-yl)methyl]-2,7-diazaspiro[3.5]nonane-7-carboxylic acid is given. What is its corresponding molecular formula?
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C21H20Cl2N6O3
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