O=Cc1ccccc1COC(=O)c1cc(C(=O)OCc2ccccc2C=O)c(C(=O)OCc2ccccc2C=O)cc1C(=O)OCc1ccccc1C=O
A rotatable bond is defined as any single non-ring bond, attached to a non-terminal, non-hydrogen atom. How many bonds in the molecule are rotatable?