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=input()
a=map(int,raw_input().split())
if (n==1):
	print 1
else:
	i=1
	ans=0
	tans=1
	current=a[0]
	while i<len(a):
#		print i,current,tans,ans
		if (abs(a[i]-current)==1):
			current=a[i]
			tans+=1
		else:
			ans=max(ans,tans)
			current=a[i]
			tans=1
		i+=1
	ans=max(ans,tans)
	print ans