COc1ccc2cc(C(=O)COC(=O)COc3ccc4c(C)cc(=O)oc4c3)ccc2c1
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?