You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
2-[[butan-2-yl-[2-(2,3-dihydro-1,4-benzothiazin-4-yl)-2-oxoethyl]amino]methyl]-3H-quinazolin-4-one is the IUPAC name of a molecule. Please give its molecular formula.
user
C23H26N4O2S
assistant