You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(E)-3-(4-butoxy-3-ethoxyphenyl)-N-(5-butyl-1,3,4-thiadiazol-2-yl)prop-2-enamide is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H29N3O3S
assistant