You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-(3-ethynyl-8-methylquinolin-6-yl)oxy-N-(1-methoxy-2-methylbut-3-yn-2-yl)propanethioamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H22N2O2S
assistant