You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
For the molecule named 2-[[6-ethyl-7-hydroxy-3-(4-methyl-1,3-thiazol-2-yl)-4-oxochromen-2-yl]methoxy]acetic acid by IUPAC nomenclature, provide its molecular formula.
user
C18H17NO6S
assistant