#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, s, e) for (int i = (int)s; i < (int)e; ++i)
#define all(a) (a).begin(), (a).end()

int main() {
    cin.tie(nullptr);
    
    int N;
    cin >> N;
    vector<int> A(N);
    rep(i, 0, N) cin >> A[i];
    set<int> s;
    int ans = 0;
    int l = 0, r = 0;
    
    while (true) {
        if (l == N) break;
        
        if (r <= N - 1 && !s.count(A[r])) {
            s.insert(A[r]);
            r++;
        } else {
            s.erase(A[l]);
            l++;
        }
        
        ans = max(ans, r - l);
    }
    
    cout << ans << '\n';
}