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