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 (1S)-1-(4-chloro-3-fluorophenyl)-2-[(3-methyl-[1,2,4]triazolo[3,4-a]phthalazin-6-yl)amino]ethanol is given. What is its corresponding molecular formula?
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C18H15ClFN5O
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