You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
ethyl 4-[9-methyl-3-[(E)-[3-[(4-methylphenyl)methyl]-4-oxo-2-sulfanylidene-1,3-thiazolidin-5-ylidene]methyl]-4-oxopyrido[1,2-a]pyrimidin-2-yl]piperazine-1-carboxylate is the IUPAC name of a molecule. Please give its molecular formula.
user
C28H29N5O4S2
assistant