Using BrBr, Cc1nsc2nc(CC(C)C)n(Cc3ccccc3)c(=O)c12 to produce Cc1nsc2nc(C(Br)C(C)C)n(Cc3ccccc3)c(=O)c12, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.