You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Can you give the molecular formula of the molecule (5S)-3-(4-chlorophenyl)-1-[(1-hydroxy-3,3-dimethylbutan-2-yl)carbamoyl]-5-methyl-6,8-dihydro-5H-imidazo[1,5-a]pyrazine-7-carboxylic acid ?
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C21H27ClN4O4
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