1, 2, 4, 3, 6, 5, 8, 7, 9, 11, 10, 12, 13, 14, 16, 15, 17, 18, 19, 20, 21, 23, 22, 24, 25, 27, 26, 28, 29, 30, 31, 32, 33, 36, 34, 37, 35, 40, 38, 41, 39, 42, 43, 44, 46, 45, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 59, 58, 60, 61, 62, 63, 64, 65, 66, 67