Using O=[N+]=O, Cn1cc([N+](=O)[O-])nc1[N+](=O)[O-] to produce Cn1c([N+](=O)[O-])nc([N+](=O)[O-])c1[N+](=O)[O-], please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.