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

int main(void)
{
    unordered_map<int, bool> h;
    int n;
    int a[100000] = {0};
    cin >> n;
    for(int i = 0; i < n; i++)
        cin>> a[i];
    int res = 0;
    int j = 0;
    for(int i = 0; i < n; i++) {
        if(h.count(a[i]) == 0)
            h[a[i]] = true;
        else {
            res = max(res, i - j);
            while(true) {
                h.erase(h.find(a[j]));
                if(a[j] == a[i])
                    break;
                j++;
            }
            h[a[i]] = true;
            j++;
        }
    }
    res = max(res, (int)h.size());
    cout << res << endl;
}