#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 ++ ) cin >> a[i];
    int res = 0;
    for (int i = 0, j = 0; i < n; i ++ ) {
        s[a[i]] ++ ;
        while (s[a[i]] > 1) {
            s[a[j]] -- ;
            j ++ ;
        }
        res = max(res, i - j + 1);
    }
    cout << res << endl;
}