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