#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define Shoyo ios_base::sync_with_stdio(0);cin.tie(NULL);
#define ff first
#define ss second
#define pii pair<ll,ll>
#define all(v) v.begin(), v.end()
#define allr(v) v.rbegin(), v.rend()
#define cl(x,y)  (x + y - 1) / y
#define el "\n"
ll Mod=998244353;
const pii adj[]={{0,1},{1,0},{-1,0},{0,-1}};
const ll N=2e5+5,M=1e5+7;
ll n;
ll dp[N];
ll val[N];
map<ll,ll> mp;
ll sol(ll i) {
    if (i==n)return 0;
ll &res=dp[i];
    if (~res)return res;
    res=1;
    for (ll j=i+1;j<n;j++) {
        if (val[j]==val[i]+1) {
            res=max(res,1+sol(j));
        }
    }
    return res;
}
void dfs(ll i) {
    cout<<mp[val[i]]<<" ";
    for (ll j=i+1;j<n;j++) {
        if (val[j]==val[i]+1) {
            dfs(j);
            break;
        }
    }
}
void solve() {
    cin>>n;
    memset(dp,-1,sizeof(dp));
    for(ll i=0;i<n;i++) {
        cin>>val[i];
        mp[val[i]]=i+1;
    }
    ll best=0,ii=0;
    for (ll i=0;i<n;i++) {
        if (sol(i)>best) {
            best=sol(i);
            ii=i;
        }
    }
    cout<<best<<el;
  dfs(ii);
 
}
int main(){
    Shoyo;
    ll t=1;
    //  if(!(cin >> t)) return 0;
    while(t--) {
        solve();
    }
    return 0;
}
 
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