You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
4-(4-bromothiophen-2-yl)-4-methyl-9-oxa-1-thia-3-azaspiro[5.5]undec-2-ene The above is the IUPAC name of a molecule. Write its molecular formula.
user
C13H16BrNOS2
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