['NC(=O)NCCCCC=O', 'CCCCCc1nnc(N)s1', 'NC=O', 'CCCCCc1nnc(NC(=O)CCCCN)s1', 'NC(N)=O', 'CCCCCc1nnc(NC(=O)CCCC)s1', 'CCCCCc1nncs1', 'NC(=O)CCCCNC(N)=O', 'CCCCC', 'NC(=O)NCCCCC(=O)Nc1nncs1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is c1nncs1.