O=C([O-])CC[C@H](NC(=O)c1ccccc1C(=O)[O-])C(=O)[O-].[Na+].[Na+].[Na+]
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?