Using O=C1C(N2C(=O)c3ccccc3C2=O)=C(N2C(=O)c3ccccc3C2=O)C(=O)C(N2C(=O)c3ccccc3C2=O)=C1N1C(=O)c2ccccc2C1=O to produce NC1=C(N)C(=O)C(N)=C(N)C1=O, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.