0(2,3):  1  2  [rn,C+]  0  1   (*,*)  (*,*)   1
1(5,2):  2  2  [i2,C-]  1  0   (2,3)  (*,*)   2,1,2
2(6,0):  3  3  [r2,rn]  3  2   (1,*)  (*,*)   2,1,2,1
3(6,1):  3  3  [r2,rn]  2  3   (1,*)  (*,*)   2,1,2,1