#include <bits/stdc++.h>
using namespace std;

int main() {
    ios::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);
    int n;
    cin >> n;
    vector<vector<int>> g(n + 1);
    vector<int> group(n + 1), hate_cnt(n + 1);
    queue<int> q_bad;
    for (int i = 1; i <= n; i++) {
        int x;
        for (cin >> x; x != 0; cin >> x) g[i].push_back(x);
        hate_cnt[i] = g[i].size();
        if (hate_cnt[i] > 1) q_bad.push(i);
    }
    while (!q_bad.empty()) {
        int p = q_bad.front(); q_bad.pop();
        if (hate_cnt[p] <= 1) continue;
        group[p] = 1 - group[p];
        hate_cnt[p] = g[p].size() - hate_cnt[p];
        for (int x : g[p]) {
            hate_cnt[x] = (group[x] == group[p] ? hate_cnt[x] + 1 : hate_cnt[x] - 1);
            if (hate_cnt[x] == 2) q_bad.push(x);
        }
    }
    cout << count(group.begin() + 1, group.end(), 0) << endl;
    for (int i = 1; i <= n; i++) if (group[i] == 0) cout << i << " ";
    cout << endl;
    return 0;
}