['CC(=O)[O-]', 'C[NH2+]Cc1ccccc1[N+](=O)[O-]', 'C[NH2+]CC(=O)[O-]', 'Cc1ccccc1[N+](=O)[O-]', 'C[NH+](C)CC(=O)[O-]', 'O=[N+]([O-])c1ccccc1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccccc1.