c an ALC problem
p cnf 8 13
1 0
-2 -3 -1 2 4 0
-2 -3 -1 5 4 0
-2 -3 -1 6 4 0
-1 2 0
-1 5 0
-1 6 0
-1 3 0
-1 1 0
-1 -6 0
-1 -7 0
-1 -4 0
-1 -8 0