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