['C#CCN', 'O=CCCNC(=O)c1ccc(F)cc1F', 'C#CCNC(=O)CCN', 'O=Cc1ccc(F)cc1F', 'C#CC', 'NC(=O)CCNC(=O)c1ccc(F)cc1F', 'C#CCNC(=O)CC', 'NC(=O)c1ccc(F)cc1F', 'Fc1cccc(F)c1', 'C#CCNC(=O)CCNC=O']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1ccccc1.