#include <iostream>
#include <cstring>
#include <algorithm>
using namespace std;
const int N = 1e5+10;
int n;
int q[N],s[N];
int main()
{
    scanf("%d", &n);
    for(int i=0;i<n;i++) scanf("%d", &q[i]);
    int res=0;
    for (int i = 0,j=0; i < n; i ++ )
    {
        s[q[i]]++;
        while(j<i&&s[q[i]]>1) s[q[j++]]--;
        res=max(res,i-j+1);
    }
    cout << res;
    return 0;
}