5. Let $f$ be a differentiable one to one function with $f(1) = 2$, $f(2) = 1$, $f(3) = 0$, $f'(1) = -6$, $f'(2) = -2$ and $f'(3) = -1/2$. Then, $(f^{-1})'(0) =$ (5).