#include <iostream>
#include <algorithm>
#include <vector>
#include <map>
#include <set>
using namespace std;
int main() {
    ios_base::sync_with_stdio(false);
    int n;
    cin >> n;
    vector<int> v(n);
    for(int &x : v) {
        cin >> x;
    }
    set<int> s;
    int j = 1;
    int ret = 1; // maximum subarray length
    for(int i = 0; i < n; ++i) {
        s.insert(v[i]);
        int repeating_number = -1;
        while(j < n) {
            s.insert(v[j]);
            if((int)s.size() != j - i + 1) {
                repeating_number = v[j];
                break;
            }
            ret = max(ret, j - i + 1);
            ++j;
        }
        int k = i;
        while(k < n and (int)s.size() != j - k + 1) {
            s.erase(v[k]);
            if(repeating_number == v[k]) {
                s.insert(v[k]);
            }
            if((int)s.size() == j - k + 1) {
                ret = max(ret, j - k + 1);
                break;
            }
            ++k;
        }
        i = k;
        --i;
    }


    cout << ret << endl;

}





/*
 8
 1 2 1 3 2 7 4 2 1 2 3 4 5 6 7 8
 */