#include <bits/stdc++.h>
using namespace std;
#define int long long
#define yes cout << "YES\n";
#define no cout << "NO\n";
void FastIO(){
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
}
/// Playlist
void solve(){
int n; cin >> n;
vector<int> vec(n);
map<int,int>freq;
for(int i = 0; i < n; i++){
cin >> vec[i];
}
int l = 0, r = 0, ans = 0;
while(r < n){
freq[vec[r]]++;
while(freq[vec[r]] > 1){
freq[vec[l]]--;
l++;
}
ans = max(ans, r-l+1);
r++;
}
cout << ans;
}
signed main(){
FastIO();
int t = 1;
//cin >> t;
while(t--){
solve();
}
return 0;
}
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