O=C(O)CC(NC(=O)/C(=C/c1ccccc1)NC(=O)c1ccccc1)C(=O)O
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?