CC(=O)O[C@@H]1[C@@H](O)C2OC3C=C(C)C(=O)[C@@H](O)[C@]3(CO)C1(C)C21CO1
A rotatable bond is defined as any single non-ring bond, attached to a non-terminal, non-hydrogen atom. Amide C-N bonds are not counted because of their high barrier to rotation.  How many rotatable bonds does the molecule have?