You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-ethyl-3-[2-[(2-oxo-3,4-dihydro-1H-quinolin-6-yl)oxy]ethyl]-2-(2-thiophen-3-ylpropyl)guanidine The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H28N4O2S
assistant