O=C1OC(c2ccc(O)c(-c3ccccc3)c2)(c2ccc(O)c(-c3ccccc3)c2)c2c(Cl)c(Cl)c(Cl)c(Cl)c21
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?