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