You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
(5E)-1-methyl-5-[[5-(N-pyridin-4-ylanilino)thiophen-2-yl]methylidene]-2-sulfanylidene-1,3-diazinane-4,6-dione is the IUPAC name of a molecule. Please give its molecular formula.
user
C21H16N4O2S2
assistant