You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
3-(furan-2-ylmethyl)-5-[[2-(3-methoxypropylamino)-4-oxopyrido[1,2-a]pyrimidin-3-yl]methylidene]-2-sulfanylidene-1,3-thiazolidin-4-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H20N4O4S2
assistant