['CCNCC#N', 'O=Cc1ccc(Cl)cc1[N+](=O)[O-]', 'CC', 'N#CCNC(=O)c1ccc(Cl)cc1[N+](=O)[O-]', 'CC#N', 'CCNC(=O)c1ccc(Cl)cc1[N+](=O)[O-]', 'CCN(C=O)CC#N', 'O=[N+]([O-])c1cccc(Cl)c1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccccc1.