You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 2-(3-cyano-4,5,6-trimethylpyridin-2-yl)sulfanyl-N-[(4-fluorophenyl)methyl]acetamide by IUPAC nomenclature, provide its molecular formula.
user
C18H18FN3OS
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