#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int INF = 1e9 + 10;
const ll INFL = 4e18;

int main() {
    int N;
    cin >> N;
    vector<int> A(N);
    for (int i = 0; i < N; i++) {
        cin >> A[i];
    }

    map<int, int> cnt1, cnt2;
    int pref = 0, suff = 0;

    for (int i = 0; i < N; i++) {
        if (cnt1[A[i]] == 0) {
            pref = i;
        } else {
            break;
        }
        cnt1[A[i]]++;
    }
    for (int i = N - 1; i >= 0; i--) {
        if (cnt2[A[i]] == 0) {
            suff = i;
        } else {
            break;
        }
        cnt2[A[i]]++;
    }

    vector<int> ans;
    for (int i = max(0, suff - 1); i <= min(pref, N - 2); i++) {
        ans.push_back(i);
    }

    cout << ans.size() << endl;
    for (int x : ans) {
        cout << ++x << ' ';
    }
    cout << endl;
}