C

#include <bits/stdc++.h>

using namespace std;

#define ll     long long
#define _test   int _TEST; cin>>_TEST; while(_TEST--)
#define ff     first
#define ss     second
#define pb     push_back
#define ppb    pop_back

int main()
{
    int n;
    cin>>n;

    vector<vector<int>> graph(n);

    for(int i=0; i<n; i++)
    {
        int v;
        cin>>v;

        v--;

        graph[i].pb(v);
    }

    vector<int> vis(n);
    vector<int> prev(n, -1);

    function<void(int)> DFS = [&](int u)
    {
        vis[u] = 1;

        for(auto v: graph[u])
        {
            if(!vis[v])
            {
                prev[v] = u;
                DFS(v);
            }
            else
            {
                vector<int> ans;

                int x = u;
                while(x != v)
                {
                    ans.pb(x+1);
                    x = prev[x];
                }

                ans.pb(v+1);

                reverse(ans.begin(), ans.end());

                cout<<ans.size()<<"\n";
                for(auto e: ans)        cout<<e<<" ";
                cout<<"\n";
                exit(0);
            }
        }

        vis[u] = 2;
    };

    for(int i=0; i<n; i++)
    {
        if(!vis[i])
            DFS(i);
    }
}