You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
4-[(3R)-3-[2-chloro-4-(methylsulfanylmethoxy)phenyl]-1,4-oxazepan-4-yl]-6-methylpyrimidin-2-amine The above is the IUPAC name of a molecule. Write its molecular formula.
user
C18H23ClN4O2S
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