#include <iostream>

using namespace std;

const int N = 100010;

int n;
int a[N], s[N];

int main()
{
    scanf("%d", &n);
    for (int i = 0; i < n; i ++ ) scanf("%d", &a[i]);

    int ans = 0;
    for (int i = 0, j = 0; i < n; i ++ )
    {
        int x = a[i];
        s[x] ++ ;
        while (s[x] > 1)
        {
            s[a[j]] -- ;
            j ++ ;
        }
        ans = max(ans, i - j + 1);
    }

    printf("%d\n", ans);
    return 0;
}