Singular Values & the SVD · Challenge problem

Let $D$ be the $8\times 9$ difference matrix with $d_{i,i} = 1$, $d_{i,i+1} = -1$ for $i = 1,\ldots,8$ and all other entries $0$ (so $(Dx)_i = x_i - x_{i+1}$). Find the product of its eight singular values.