#include <iostream>
#include <vector>
#include <map>

using namespace std;
using ll = long long;

constexpr int iINF = 1'000'000'000;
constexpr ll llINF = 1'000'000'000'000'000'000;

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

    // 前と後ろから見ます。
    map<int, int> mp;
    vector<bool> front(N, true);
    vector<bool> back(N, true);

    {
        mp.clear();
        for (int i = 0; i < N; i++) {
            if (0 < i) front[i] = front[i - 1];
            if (0 < mp[A[i]]) front[i] = false;
            mp[A[i]]++;
        }
    }
    {
        mp.clear();
        for (int i = N - 1; 0 <= i; i--) {
            if (i < N - 1) back[i] = back[i + 1];
            if (0 < mp[A[i]]) back[i] = false;
            mp[A[i]]++;
        }
    }

    vector<int> ans;
    for (int i = 0; i < N - 1; i++) {
        if (front[i] && back[i + 1]) ans.push_back(i + 1);
    }

    cout << ans.size() << "\n";
    for (int i = 0; i < ans.size(); i++) {
        cout << ans[i] << (i == ans.size() - 1 ? "" : " ");
    }
    cout << "\n";
}