['CCNCC#N', 'Cc1cc(C=O)ccc1[N+](=O)[O-]', 'CC', 'Cc1cc(C(=O)NCC#N)ccc1[N+](=O)[O-]', 'CC#N', 'CCNC(=O)c1ccc([N+](=O)[O-])c(C)c1', 'CCN(C=O)CC#N', 'Cc1ccccc1[N+](=O)[O-]']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccccc1.