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