#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 5;
int n, a[N], s[N], res = 0;
int main() {
cin >> n;
for (int i = 0, j = 0; i < n; i++) {
cin >> a[i];
++s[a[i]];
while (s[a[i]] > 1) --s[a[j++]];
res = max(res, i - j + 1);
}
cout << res;
return 0;
}