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

#define ll long long
#define pb push_back
#define mp make_pair
#define pii pair<int, int>
#define fi first
#define se second

const int maxn = 3e5;

int n;
vector<int> graph[1 + maxn];
vector<pii > edges;
int comp[1 + maxn];
queue<int> q;

void solve() {
    cin >> n;
    for(int i = 1; i <= n; i++) {
        while(true) {
            int j;
            cin >> j;
            if(j == 0) {
                break;
            }
            if(i < j) {
                edges.pb(mp(i, j));
            }
            graph[i].pb(j);
        }
    }
    for(int i = 1; i <= n; i++) {
        q.push(i);
    }
    while(!q.empty()) {
        int cur = q.front();
        q.pop();
        int cnt = 0;
        for(int nei : graph[cur]) {
            if(comp[nei] == comp[cur]) {
                cnt++;
            }
        }
        if(cnt > 1) {
            comp[cur] ^= 1;
            for(int nei : graph[cur]) {
                q.push(nei);
            }
        }
    }
    vector<int> ans;
    for(int i = 1; i <= n; i++) {
        if(comp[i] == 1) {
            ans.pb(i);
        }
    }
    cout << (int) ans.size() << "\n";
    for(int x : ans) {
        cout << x << " ";
    }
    cout << "\n";
}

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    int T = 1;
    //cin >> T;
    while(T--) {
        solve();
    }
}