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