// UUID: c1a69833-4b9c-46b5-92b6-14b4e1004893
#include <bits/stdc++.h>
using namespace std;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n;
    cin >> n;
    vector<vector<int>> hate(n);
    vector<int> counter(n,0);
    vector<int> v(n);
    for (int i=0; i<n; i++) {
        int a;
        cin >> a;
        while (a!=0) {
            hate[i].push_back(a-1);
            counter[i]++;
            cin >> a;
        }
    }
    int k=n;
    vector<int> groups(n,0);
    while (k>0) {
        if (counter[v[k-1]]<2) {
            v.pop_back();
        }
        else {
            for (int i:hate[v[k-1]]) {
                if (groups[i]==groups[v[k-1]]) {
                    counter[i]--;
                    counter[v[k-1]]--;
                }
                else {
                    counter[i]++;
                    counter[v[k-1]]++;
                    if (counter[i]==2) {
                        v.push_back(i);
                    }
                }
            }
            groups[v[k-1]]=1-groups[v[k-1]];
            v.pop_back();
            k--;
        }
    }
    int m=0;
    for (int i=0; i<n; i++) {
        if (groups[i]==0) {
            m++;
        }
    }
    cout << m << "\n";
    for (int i=0; i<n; i++) {
        if (groups[i]==0) {
            cout << i+1 << " ";
        }
    }
}