[[1, 2, 3], [4, 5, 6]]
[4,1,2,3,6,5]
[[1, 2, 3, 4, 5], [6, 7, 8, 9, 10], [11, 12, 13, 14, 15]]
[11,6,1,2,3,4,5,10,15,14,13,12,7,8,9,9,8]
m = matrix.size()n = matrix[0].size()1 0