#include <bits/stdc++.h>
using namespace std;
using ll = long long;

template<class T> istream& operator >> (istream& is, vector<T>& vec) {
    for(T& x : vec) is >> x;
    return is;
}

template<class T> ostream& operator << (ostream& os, const vector<T>& vec) {
    if(vec.empty()) return os;
    os << vec[0];
    for(auto it = vec.begin(); ++it != vec.end(); ) os << ' ' << *it;
    return os;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n;
    cin >> n;
    vector<int> a(n);
    cin >> a;
    map<int,int> mp, mp2;
    int r = -1;
    for(int i = 0; i < n; i++){
        mp[a[i]]++;
        if(mp[a[i]] == 1) r = i + 1;
        else break;
    }
    int l = n;
    for(int i = n - 1; i >= 0; i--){
        mp2[a[i]]++;
        if(mp2[a[i]] == 1) l = i;
        else break;
    }
    vector<int> ans;
    for(int i = max(1, l); i <= r && i <= n - 1; i++){
        ans.push_back(i);
    }
    cout << ans.size() << '\n' << ans << '\n';
}