#include <bits/stdc++.h>
#include <atcoder/all>
#define rep(i,n) for(int (i)=0;(i)<(n);(i)++)
#define rep2(i,m,n) for(int (i)=(m);(i)<(n);(i)++)
#define rep2ll(i,m,n) for(ll (i)=(m);(i)<(n);(i)++)
#define ALL(obj) (obj).begin(), (obj).end()
#define rALL(obj) (obj).rbegin(), (obj).rend()
using namespace std;
using ll = long long;
using P = pair<ll,ll>;
using mint = atcoder::modint998244353;
using VL = vector<ll>;
using VVL = vector<VL>;
using VVVL = vector<VVL>;
using VM = vector<mint>;
using VVM = vector<VM>;
using VVVM = vector<VVM>;
using VD = vector<double>;
using VVD = vector<VD>;
using VVVD = vector<VVD>;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }


int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    ll n; cin>>n;
    VL a(n); rep(i,n) cin>>a[i];
    ll L, R;
    set<ll> s;
    rep(i,n){
        if(s.count(a[i])) break;
        s.insert(a[i]);
        R = i + 1;
    }
    s.clear();
    for(int i=n-1; i>=0; i--){
        if(s.count(a[i])) break;
        s.insert(a[i]);
        L = i - 1;
    }
    chmax(L, 0LL);
    chmin(R, n-1);
    
    VL ans;
    rep2(i,L,R) ans.push_back(i);
    cout<<ans.size()<<'\n';
    for(auto x:ans) cout<<x+1<<' ';
    cout<<'\n';

    
    return 0;
}