You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2,3,4a,5,6,7,8,8a-octahydrobenzo[b][1,4]oxazin-4-yl-(2-fluoro-5-sulfanylphenyl)methanone is the IUPAC name of a molecule. Please give its molecular formula.
user
C15H18FNO2S
assistant