1 0 0 0 0 1 0 0 0 0 1 0
0 1 0 0 1 0 0 0 0 0 -1 1/2
1 0 0 0 0 1 0 0 0 0 -1 1/2
0 1 0 0 1 0 0 0 0 0 1 0