['CC(N)C(N)=O', 'CCCc1ccc(C=O)cc1', 'CCC(N)=O', 'CCCc1ccc(C(N)=O)cc1', 'CC(NC=O)C(N)=O', 'CCCc1ccccc1', 'CCC', 'CC(NC(=O)c1ccccc1)C(N)=O']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccccc1.