Write a method to sort a two-dimensional array using the following header:
public static void sort(int m[][])
The method performs a primary sort on rows and a secondary sort on columns.

For example, the following array

{{4, 2},{1, 7},{4, 5},{1, 2},{1, 1},{4, 1}}

will be sorted to

{{1, 1},{1, 2},{1, 7},{4, 1},{4, 2},{4, 5}}.