You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Convert the IUPAC name of a molecule N-[4-fluoro-6-[(3Z)-4-[[(E)-N'-(4-methoxyphenyl)sulfonylcarbamimidoyl]amino]buta-1,3-dien-2-yl]-1,3-benzothiazol-2-yl]acetamide into molecular formula.
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C21H20FN5O4S2
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