length = 21 9, 11, 12, 13 0, 8, 14, 10 15, 1, 5, 4 6, 3, 2, 7 9, 11, 12, 13 3, 8, 14, 10 15, 1, 5, 4 6, 0, 2, 7 9, 11, 12, 13 3, 8, 0, 10 15, 1, 5, 4 6, 14, 2, 7 0, 11, 12, 13 3, 8, 9, 10 15, 1, 5, 4 6, 14, 2, 7 1, 11, 12, 13 3, 8, 9, 10 15, 0, 5, 4 6, 14, 2, 7 1, 11, 12, 13 3, 8, 9, 0 15, 10, 5, 4 6, 14, 2, 7 1, 11, 12, 13 3, 8, 9, 2 15, 10, 5, 4 6, 14, 0, 7 1, 11, 12, 13 3, 0, 9, 2 15, 10, 5, 4 6, 14, 8, 7 1, 11, 12, 13 3, 4, 9, 2 15, 10, 5, 0 6, 14, 8, 7 1, 11, 0, 13 3, 4, 9, 2 15, 10, 5, 12 6, 14, 8, 7 1, 11, 3, 13 0, 4, 9, 2 15, 10, 5, 12 6, 14, 8, 7 1, 11, 3, 13 5, 4, 9, 2 15, 10, 0, 12 6, 14, 8, 7 1, 11, 3, 0 5, 4, 9, 2 15, 10, 13, 12 6, 14, 8, 7 1, 11, 3, 4 5, 0, 9, 2 15, 10, 13, 12 6, 14, 8, 7 1, 11, 3, 4 5, 6, 9, 2 15, 10, 13, 12 0, 14, 8, 7 1, 11, 3, 4 5, 6, 9, 2 15, 10, 0, 12 13, 14, 8, 7 1, 0, 3, 4 5, 6, 9, 2 15, 10, 11, 12 13, 14, 8, 7 1, 2, 3, 4 5, 6, 9, 0 15, 10, 11, 12 13, 14, 8, 7 1, 2, 3, 4 5, 6, 9, 8 15, 10, 11, 12 13, 14, 0, 7 1, 2, 3, 4 5, 6, 9, 8 0, 10, 11, 12 13, 14, 15, 7 1, 2, 3, 4 5, 6, 0, 8 9, 10, 11, 12 13, 14, 15, 7 1, 2, 3, 4 5, 6, 7, 8 9, 10, 11, 12 13, 14, 15, 0