['Cn1ccs/c1=N/C=O', 'Cc1noc(-c2ccccc2)n1', 'Cc1ncon1', 'Cn1ccs/c1=N/C(=O)c1ccccc1']
The Murcko scaffold (minmal number of connected rings) of <smiles></smiles> is O=C(/N=c1\[nH]ccs1)c1ccc(-c2ncno2)cc1.