['CO', 'CCc1nc(C)cc(NCCN)n1', 'CCN', 'COCCc1nc(C)cc(N)n1', 'NCCN', 'COCCc1nccc(C)n1', 'CCOC', 'Cc1cc(NCCN)ncn1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1cncnc1.