You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule (2S,4R)-4-(1,3-benzothiazol-2-yloxy)-1-[(2S)-2-(3,4-difluoroanilino)propanoyl]pyrrolidine-2-carboxamide into molecular formula.
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C21H20F2N4O3S
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