You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
N-benzyl-N-(4,7-dimethyl-1,3-benzothiazol-2-yl)-3-methyl-1,2-oxazole-5-carboxamide The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H19N3O2S
assistant