#include<iostream>
#include<algorithm>
using namespace std;

const int N = 100010, MAX = 100010;
int a[N], cnt[MAX];

int main()
{
    int n, res = 0, i = 0, j = 0;
    cin >> n;
    for (int i = 0; i < n ; i++) scanf("%d", &a[i]);
    while (j < n)
    {
        cnt[a[j]]++;
        while (cnt[a[j]] > 1) cnt[a[i++]]--;
        res = max(res, j - i + 1);
        j++;
    }
    cout << res << endl;

}