#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")



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