8 8
 1: 1 3 7 8
 2: 4 5 7 8
 3: 2 4 6 7
 4: 2 3 6 8
 5: 2 5 7 8
 6: 2 3 4 8
 7: 1 4 5 7
 8: 2 5 7 8