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