0, 1, 1, 2, 2, 1, 4, 4, 3, 2, 5, 5, 4, 3, 1, 7, 7, 6, 5, 3, 2, 8, 8, 7, 6, 4, 3, 1, 11, 11, 10, 9, 7, 6, 4, 3, 13, 13, 12, 11, 9, 8, 6, 5, 2, 15, 15, 14, 13, 11, 10, 8, 7, 4, 2, 16, 16, 15, 14, 12, 11, 9, 8, 5, 3, 1, 19, 19, 18, 17, 15, 14, 12, 11, 8, 6, 4, 3, 20, 20, 19, 18, 16, 15, 13, 12, 9, 7