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 (3-fluorocyclobutyl)-[7-(pyridin-4-ylmethoxy)-5-thia-2-azaspiro[3.4]octan-2-yl]methanone into molecular formula.
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C17H21FN2O2S
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