You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
methyl 3-[[2-[1-oxo-4-(pyridin-3-ylmethyl)phthalazin-2-yl]acetyl]amino]thiophene-2-carboxylate The above is the IUPAC name of a molecule. Write its molecular formula.
user
C22H18N4O4S
assistant