//
// Created by darian on 07.06.24.
//

#include <bits/stdc++.h>
using namespace std;
using ll = long long;

int main() {
    int n; cin >> n;
    vector<ll> in(n);
    for (auto &e : in) cin >> e;
    int lo = 0;
    int hi = 0;
    int max_count = 1;
    set<ll> current = {in[0]};

    while (hi < n - 1) {
        hi++;
        while (current.count(in[hi])) {
            current.erase(in[lo]);
            lo++;
        }
        current.insert(in[hi]);
        max_count = max(max_count, (int)current.size());
    }
    cout << max_count << endl;
}