You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
3-[2-[(4S,5S)-3-(3-chloro-4-methoxyphenyl)-5-pyridin-2-yl-2-sulfanylideneimidazolidin-4-yl]pyrrol-1-yl]benzoic acid is the IUPAC name of a molecule. Please give its molecular formula.
user
C26H21ClN4O3S
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