CCOC(=O)N/N=C1/C[C@@H](O)[C@@H](O)[C@@H]2[C@@H]3C(=O)N(C(C)(C)C)C(=O)[C@H]3CC[C@@H]12
Heavy atom refers to any atom that is not hydrogen. The heavy atoms in molecules are carbon, oxygen, nitrogen, and sulfur. How many heavy atoms are in the molecule?