['c1cn[nH]c1', 'Cc1cc(Cl)nc(C(C)C)n1', 'CCC', 'Clc1cc(Cn2cccn2)ncn1', 'Cn1cccn1', 'CC(C)c1nccc(Cl)n1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1cnn(Cc2ccncn2)c1.