p cnf 12 22
-1 -4 0
-1 -7 0
-1 -10 0
-4 -7 0
-4 -10 0
-7 -10 0
-2 -5 0
-2 -8 0
-2 -11 0
-5 -8 0
-5 -11 0
-8 -11 0
-3 -6 0
-3 -9 0
-3 -12 0
-6 -9 0
-6 -12 0
-9 -12 0
3 2 1 0
6 5 4 0
9 8 7 0
12 11 10 0