// UUID: 2f59b4e5-e689-4c51-9e1f-9c9537aaf451
#include <bits/stdc++.h>
using namespace std;
#define int long long

template<class t>
std::ostream& operator<<(std::ostream& os, std::vector<t>v){
    for(t a : v){
        os << a<< " ";
    }
    os << "\n";
    return os;
}
template<class t>
std::istream& operator>>(std::istream& os, std::vector<t>&v){
    for(t& a : v){
        os >> a;
    }
    return os;
}

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int n;
    cin >> n;
    vector<vector<int>>v(n);
    vector<bool>team(n);
    queue<int>q1,q2;
    for(int i = 0; i < n; i++){
        int a;
        cin >>a;
        while(a){
            v[i].push_back(a-1);
            cin >> a;
        }
        q2.push(i);
    }
    
    while(!q2.empty()){
        swap(q2,q1);
        while(!q1.empty()){
            int cs = q1.front();
            q1.pop();
            int count = 0;
            for(int i : v[cs])if(team[i] == team[cs])count++;
            if(count>=2){
                team[cs] = !team[cs];
                for(int i : v[cs]){
                    q2.push(i);
                }
            }
            
        }
    
    }
    cout << count(team.begin(),team.end(),1) << "\n";
    for(int i = 0; i< n; i++){
        if(team[i])cout<< i+1<<" ";
    }
    //cout <<v;
}