When Xellos was doing a practice course in university, he once had to measure the intensity of an effect that slowly approached equilibrium. A good way to determine the equilibrium intensity would be choosing a sufficiently large number of consecutive data points that seems as constant as possible and taking their average. Of course, with the usual sizes of data, it's nothing challenging — but why not make a similar programming contest problem while we're at it? You're given a sequence of n data points a 1 , ..., a n . There aren't any big jumps between consecutive data points — for each 1 ≤ i < n , it's guaranteed that | a i + 1 - a i | ≤ 1 . A range l , r of data points is said to be almost constant if the difference between the largest and the smallest value in that range is at most 1 . Formally, let M be the maximum and m the minimum value of a i for l ≤ i ≤ r ; the range l , r is almost constant if M - m ≤ 1 . Find the length of the longest almost constant range. The first line of the input contains a single integer n ( 2 ≤ n ≤ 100 000 ) — the number of data points. The second line contains n integers a 1 , a 2 , ..., a n ( 1 ≤ a i ≤ 100 000 ). Print a single number — the maximum length of an almost constant range of the given sequence. In the first sample, the longest almost constant range is 2, 5 ; its length (the number of data points in it) is 4. In the second sample, there are three almost constant ranges of length 4 : 1, 4 , 6, 9 and 7, 10 ; the only almost constant range of the maximum length 5 is 6, 10 .