You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-[2-[2-[(3Z,5Z,8Z)-7-methylidene-2H-thionin-8-yl]ethoxy]ethyl]pyrrolidin-3-ol is the IUPAC name of a molecule. Please give its molecular formula.
user
C17H25NO2S
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