Revision control
++ 0, 3, 5, 2, 6, 9, 7, 8, 1
++ 6, 8, 2, 5, 7, 1, 4, 9, 3
++ 1, 9, 7, 8, 3, 4, 5, 6, 2
++ 8, 2, 6, 1, 9, 5, 3, 4, 7
++ 3, 7, 4, 6, 8, 2, 9, 1, 5
++ 9, 5, 1, 7, 4, 3, 6, 2, 8
++ 5, 1, 9, 3, 2, 6, 8, 7, 4
++ 2, 4, 8, 9, 5, 7, 1, 3, 6
++ 7, 6, 3, 4, 1, 8, 2, 5, 9