#include <iostream>
#include <vector>
#include <algorithm>
#include <map>
#include <queue>
#include <set>
#include <random>
#include <iomanip>
#include <string>
#include <cmath>
#include <complex>
using namespace std;
typedef long long ll;
#define rep(i, n) for(int i = 0; i < (n); i++)

template<class T>
using vi = vector<T>;

template<class T>
using vii = vector<vi<T>>;

template<class T>
using viii = vector<vii<T>>;

template<class T>
using viiii = vector<viii<T>>;

using P = pair<ll, int>;

void chmin(ll & x, ll y) { x = min(x, y); }

void chmax(ll& x, ll y) { x = max(x, y); }

int main()
{
    int n;
    cin >> n;
    vi<int> a(n);
    rep(i, n) cin >> a[i];

    int l = 0, r = n;
    set<int> st;
    rep(i, n) {
        if (st.count(a[i])) break;
        st.insert(a[i]);
        l = i + 1;
    }

    st.clear();
    for (int i = n - 1; i >= 0; i--) {
        if (st.count(a[i])) break;
        st.insert(a[i]);
        r = i;
    }

    r = max(r, 1);
    l = min(l, n - 1);
    int ans = l - r + 1;
    if (ans <= 0) {
        cout << 0 << endl;
        cout << endl;
        return 0;
    }
    cout << ans << endl;
    for (int i = r; i <= l; i++) cout << i << " \n"[i == l];
    return 0;
}