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.

输入描述:

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 a1, a2, ..., an (1 ≤ ai ≤ 100 000).

输出描述:

Print a single number — the maximum length of an almost constant range of the given sequence.

备注:

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].