A:= [[ 2, 3, 1, 4, 5,-6], 
     [ 2,-4,-6, 3, 5, 1], 
     [ 5, 3, 6,-1, 4,-2], 
     [ 2, 3, 6, 1, 4, 5], 
     [-6, 3, 2, 5, 4,-1], 
     [ 3,-2, 1, 6, 4, 5]]: