['C#CCN', 'CC(=O)N[C@H](CC=O)c1ccc(C)cc1', 'CC=O', 'C#CCNC(=O)C[C@@H](N)c1ccc(C)cc1', 'C#CC', 'CC(=O)N[C@H](CC(N)=O)c1ccc(C)cc1', 'CC(N)=O', 'C#CCNC(=O)CCc1ccc(C)cc1', 'Cc1ccccc1', 'C#CCNC(=O)CCNC(C)=O']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccccc1.