//
//  Playlist
//  
//
//  Created by Krish Narsaria on 05/01/25.
//
 
#include <bits/stdc++.h>
using namespace std;
#define ll long long
void solve() {
    unordered_map<int, int> lastIndex;
    int n, a, ans = 0, start = 0;
    cin >> n;
    for (int i = 0; i < n; i++) {
        cin >> a;
        if (lastIndex.find(a) != lastIndex.end() && lastIndex[a] >= start) {
            start = lastIndex[a] + 1;
        }
        lastIndex[a] = i;
        ans = max(ans, i - start + 1);
    }
    cout << ans << "\n";
}
int main(){solve();}

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