In the town of Pirates, Captain Jack is the best pirate. Captain Smith is jealous of Jack's popularity. So he challenged Jack to solve the following puzzle:
Given an array A, find the length of the largest contiguous sub-array such that the difference between any two consecutive elements in the sub-array is 1. Captain Jack is a little confused, so he called you, a programmer, for solving this puzzle.

INPUT

First line of input contains a number N i.e. the number of elements in array A. The next line contains N space separated integers representing elements of array.

OUTPUT

Print the largest length of contiguous sub-array satisfying the above given property.

CONSTRAINTS

1 ≤ N ≤ 100000     
0 ≤ A[ i ] ≤ 100000 

SAMPLE INPUT
6
1 3 5 7 8 9

SAMPLE OUTPUT
3
n = int(raw_input())
a = [int(x) for x in raw_input().split()]

l = m = 1
for i in xrange(1, n):
	if abs(a[i] - a[i - 1]) == 1:
		l += 1
		m = max(m, l)
	else:
		l = 1

print m