You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
1-[(4-bromo-2-phenoxyphenyl)methyl]-3-[(4,5-dimethyl-1,3-oxazol-2-yl)methyl]-2-methylguanidine The above is the IUPAC name of a molecule. Write its molecular formula.
user
C21H23BrN4O2
assistant