['C#CCN', 'O=CCCCNC(=O)c1ccccc1', 'O=Cc1ccccc1', 'C#CCNC(=O)CCCN', 'C#CC', 'NC(=O)CCCNC(=O)c1ccccc1', 'C#CCNC(=O)CCC', 'NC(=O)c1ccccc1', 'c1ccccc1', 'C#CCNC(=O)CCCNC=O']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccccc1.