\begin{bmatrix}
-1 &  0 &  0 &  1 &  0 &  0 \\
 2 & -1 &  0 &  0 &  0 &  0 \\
 0 &  1 & -5 &  0 & -1 &  0 \\
 0 &  0 &  3 & -1 &  0 &  0 \\
 0 &  1 &  2 &  0 &  1 & -1 \\
 0 & -1 &  0 & -1 &  0 &  1 \\
 0 &  1 &  0 &  1 &  0 & -1 \\
 0 &  0 &  0 &  0 &  0 &  0 \\
-1 &  0 &  0 &  0 &  0 &  0 \\
 0 &  0 &  0 &  0 &  1 &  0 \\
 0 &  0 &  0 &  0 & -1 &  0
\end{bmatrix}