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 1-[(1R,15R,17S,18S)-17-ethyl-7-hydroxy-3,13-diazapentacyclo[13.3.1.02,10.04,9.013,18]nonadeca-2(10),4(9),5,7-tetraen-3-yl]-2-(4-methylpiperazin-1-yl)ethanone into molecular formula.
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C26H36N4O2
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