p cnf 30 81
-1 -6 0
-1 -11 0
-1 -16 0
-1 -21 0
-1 -26 0
-6 -11 0
-6 -16 0
-6 -21 0
-6 -26 0
-11 -16 0
-11 -21 0
-11 -26 0
-16 -21 0
-16 -26 0
-21 -26 0
-2 -7 0
-2 -12 0
-2 -17 0
-2 -22 0
-2 -27 0
-7 -12 0
-7 -17 0
-7 -22 0
-7 -27 0
-12 -17 0
-12 -22 0
-12 -27 0
-17 -22 0
-17 -27 0
-22 -27 0
-3 -8 0
-3 -13 0
-3 -18 0
-3 -23 0
-3 -28 0
-8 -13 0
-8 -18 0
-8 -23 0
-8 -28 0
-13 -18 0
-13 -23 0
-13 -28 0
-18 -23 0
-18 -28 0
-23 -28 0
-4 -9 0
-4 -14 0
-4 -19 0
-4 -24 0
-4 -29 0
-9 -14 0
-9 -19 0
-9 -24 0
-9 -29 0
-14 -19 0
-14 -24 0
-14 -29 0
-19 -24 0
-19 -29 0
-24 -29 0
-5 -10 0
-5 -15 0
-5 -20 0
-5 -25 0
-5 -30 0
-10 -15 0
-10 -20 0
-10 -25 0
-10 -30 0
-15 -20 0
-15 -25 0
-15 -30 0
-20 -25 0
-20 -30 0
-25 -30 0
5 4 3 2 1 0
10 9 8 7 6 0
15 14 13 12 11 0
20 19 18 17 16 0
25 24 23 22 21 0
30 29 28 27 26 0