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