#include <iostream>
#include <vector>
#include <set>
using namespace std;
int main() {
int n;
cin >> n;
vector<int> v(n);
for (int i = 0; i < n; ++i) {
cin >> v[i];
}
set<int> s;
int ans = 0;
int count = 1;
int i=1;
s.insert(v[0]);
while(i<n) {
s.insert(v[i]);
count++;
if (s.size() < count) {
count=0;
s.clear();
} else {
ans = max(ans, count);
i++;
}
}
cout << ans << endl;
return 0;
}
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