You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule 2-(2-fluorophenyl)-1-[(8S)-8-(pyridin-3-yloxymethyl)-5-oxa-2-azaspiro[3.4]octan-2-yl]ethanone into molecular formula.
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C20H21FN2O3
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