#include <iostream>
#include <vector>


using namespace std;
vector<int> nums;
int res = 0;
int s[100010];
void solve(vector<int>& nums) {
    for (int i = 0, j = 0; i < nums.size(); i++) {
        s[nums[i]]++;

        while (s[nums[i]] > 1) {
            s[nums[j]]--;
            j++;
        }

        res = max(res, i - j + 1);
    }
}

int main()
{
    int n;
    cin >> n;

    while (n -- ) {
        int x;
        cin >> x;
        nums.push_back(x);
    }

    solve(nums);
    cout << res << endl;

    return 0;
}