[{"from": "human", "value": "Create a molecule that satisfies the conditions outlined in the description. The molecule is a (13)C-modified compound that is urea in which the carbon is present as its (13)C isotope. It is a (13)C-modified compound and a one-carbon compound."}, {"from": "gpt", "value": "[13C][=Branch1][C][=O][Branch1][C][N][N]"}]