#include <iostream>
using namespace std;
const int N = 100010;
int a[N], s[N];
int main()
{
int n;
cin >> n;
for (int i = 0; i < n; i ++) cin >> a[i];
int res = 0;
for (int i = 0, j = 0; i < n; i ++)
{
s[a[i]] ++;
while (j < i && s[a[i]] > 1)
{
s[a[j]] --;
j ++;
}
res = max(res, i - j + 1);
}
cout << res << endl;
return 0;
}