You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-[(8R)-8-[(2-methyl-1,3-thiazol-4-yl)methoxy]-5-oxa-2-azaspiro[3.5]nonan-2-yl]-2-thiophen-3-ylethanone is the IUPAC name of a molecule. Please give its molecular formula.
user
C18H22N2O3S2
assistant