N = 5;
M = 6;
R = 2;
C = 2;
a = [|5,4,2,6,6,2,
     |4,10,1,8,2,4,
     |1,9,3,10,10,5,
     |6,4,8,3,1,4,
     |6,8,4,10,2,10|];