#include <bits/stdc++.h>

using namespace std;

int main()
{
    int n;
    cin >> n;
    int pos = 0;
    map<int, int> m;
    int maxl = 0;
    vector<int> v(n);
    for(int i = 0; i < n; i++) {
        cin >> v[i];
        if(pos == 0) {
            m[v[i]]++;
            maxl = i;
            if(m.size() == 3) {
                if(m[v[i]] == 1)
                    m.erase(v[i]);
                else
                    m[v[i]]--;
                pos = i;
                maxl = i;
            }
        }
    }
    if(pos == 0) maxl++;

    int i = 0;
    while(true)
    {
        while(m.size() != 1 && i < n)
        {
            if(m[v[i]] == 1)
                m.erase(v[i]);
            else
                m[v[i]]--;
            i++;
        }
        if(i == n || i == pos) break;
        for(int j = pos; j < n; j++) {
            m[v[j]]++;
            if(m.size() > 2) {
                pos = j;
                maxl = max(maxl, j - i);
                if(m[v[j]] == 1)
                     m.erase(v[j]);
                else
                    m[v[j]]--;

                break;
            }
        }
    }
    if(m.size() < 3) {
        maxl = max(maxl, n - i);
    }
    cout << maxl;
}