N = 12;
M = 12;
R = 7;
C = 6;
a = [|7,5,12,2,6,13,10,10,2,11,7,1,
     |3,16,5,14,6,19,1,15,12,20,9,13,
     |13,8,18,13,5,19,11,2,7,16,9,8,
     |19,15,12,8,17,1,14,1,10,11,3,2,
     |18,12,1,17,3,9,17,16,6,10,13,10,
     |11,19,15,12,13,10,6,8,14,10,7,5,
     |8,1,3,1,6,14,15,4,1,10,13,2,
     |10,16,1,10,6,6,17,7,11,18,5,19,
     |3,13,2,11,6,11,10,7,4,7,17,14,
     |15,20,6,11,3,8,11,17,8,16,17,9,
     |20,9,3,2,12,13,10,5,14,16,13,1,
     |13,1,9,4,5,12,12,12,2,10,6,5|];