[Digger]

R1: 12 9 1 2
R2: 4 2 1 3
R3: 1 8 2 3
R4: 6 4 1 2
R5: 6 3 1 2
R6: 8 3 1 2
r7: 1 2 3 4
r8: 1 2 3 4
r9: 1 2 3 4
r10: 1 2 3 4
r11: 1 2 3 4
r12: 1 2 3 4