You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name 1-[3-(4-chloro-3,5-dimethylpyrazol-1-yl)phenyl]-2-(2-methyl-1,3-benzoxazol-5-yl)ethanone into its molecular formula.
user
C21H18ClN3O2
assistant