#include <bits/stdc++.h>
using namespace std;

int main() {
	int n; cin >> n;
	vector<int> arr(n);
	for(int i = 0; i < n; i++)
	cin >> arr[i];
	
	vector<int> diff(n);
	for(int i = 1; i < n; i++){
		diff[i] = arr[i] - arr[i-1];
	}
	vector<int> pref(n);
	vector<int> suff(n);
	pref[1] = 1;
	int len = INT_MIN;
	for(int i = 2; i < n; i++){
		if(diff[i] == diff[i-1])
		pref[i] = pref[i-1]+1;
		else
		pref[i] = 1;
		
		len = max(len, pref[i]);
	}
	suff[n-1] = 1;
	for(int i = n-2; i >= 1; i--){
		if(diff[i] == diff[i+1])
		suff[i] = suff[i+1]+1;
		else
		suff[i] = 1;
	}
	int max_len = 0;
	for(int i = 1; i < n; i++){
		if(abs(diff[i]) == abs(diff[i+1])){
			if(i >=2 && i < n-2)
			max_len = pref[i-1]+suff[i+2]+2;
			else if(i < n-2)
			max_len = suff[i+2]+3;
			else if(i >= 2)
			max_len = suff[i+2]+3;
			else
			max_len = 2;
			
			len = max(len, max_len);
		}
	}
	cout << len+1;
	return 0;
}