#include <bits/stdc++.h>

#define forn(i, n) for (int i = 0; i < int(n); i++)

using namespace std;
vector < vector <int> > spTAB_min;
vector < vector <int> > spTAB_max;

void build_spTAB(vector <int> &arr){
    int n = arr.size();
    int k = (int)log2(n);

    for (int i = 0; i < n; i++){
        spTAB_min[0][i] = arr[i];
        spTAB_max[0][i] = arr[i];
    }
    for (int j = 1; j <= k; j++) {
        for (int i = 0; i + pow(j, 2) <= n; i++) {
            spTAB_min[j][i] = min (spTAB_min[j - 1][i], spTAB_min[j - 1][i + pow(j, 2)]);
            spTAB_max[j][i] = max (spTAB_max[j - 1][i], spTAB_max[j - 1][i + pow(j, 2)]);
        }
    }
}

int get_max(int R, int L){
     int k = log2(R - L + 1);
     cout << "MAX FROM " << R << " TO " << L << " = " << min(spTAB_min[k][L], spTAB_min[k][R - pow(k, 2) + 1]) << endl;
     return max(spTAB_max[k][L], spTAB_max[k][R - pow(k, 2) + 1]);
}

int get_min(int R, int L){
     int k = log2(R - L + 1);
     cout << "MIN FROM " << R << " TO " << L << " = " << min(spTAB_min[k][L], spTAB_min[k][R - pow(k, 2) + 1]) << endl;
     return min(spTAB_min[k][L], spTAB_min[k][R - pow(k, 2) + 1]);
}

int main()
{
    int n;
    cin >> n;

    vector <int> a(n);
    spTAB_min.resize((int)log2(n)+1, vector <int> (n));
    spTAB_max.resize((int)log2(n)+1, vector <int> (n));

    forn(i, n){
        cin >> a[i];
    }

    build_spTAB(a);

    int ans = 0, r = 0;

    for(int l = 0; l < n; l++){
        while(r < n - 1 && get_max(l, r+1) - get_min(l, r+1) <= 1){
            r++;
        }
        if(get_max(l, r) - get_min(l, r) <= 1){
            ans = max(ans, r - l + 1);
        }
    }

    cout << ans;

    return 0;
}