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

int main() 
{
    int n;
    cin >> n;
    int left = -1;
    int indexLeft = 0, length = 0;
    for(int i = 0; i < n; ++i)
    {
        int elem;
        cin >> elem;
        if(abs(left - elem) <= 1)
        {
            length = max(length, i - indexLeft + 1);
        }
        else
        {
            indexLeft = i;
        }
        left = elem;
    }
    cout << length;
}
// 64 位输出请用 printf("%lld")