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

int main() {
	ios_base::sync_with_stdio(0); cin.tie(0);

    int n;
    cin>>n;
    vector<vector<int>> g(n+1);
    vector<int> c(n+1,1);
    queue<int> q;
    for (int i=1;i<=n;i++) {
        int a;
        while (true){
            cin>>a;
            if (!a) break;
            g[i].push_back(a);
        }
        if (g[i].size()>1) q.push(i);
    }
    while (!q.empty()){
        int v=q.front();
        q.pop();
        int cnt=0;
        for (int i : g[v]) cnt+=(c[v]==c[i]);
        if (cnt<2) continue;

        c[v]=3-c[v];
        
        for (int to : g[v]){
            cnt=0;
            for (int i : g[to]) cnt+=(c[v]==c[i]);
            if (cnt>1) q.push(to);
        }
    }
    vector<int> ans;
    for (int i=1;i<=n;i++) if (c[i]==1) ans.push_back(i);
    cout<<ans.size()<<"\n";
    for (int i : ans) cout<<i<<" ";
}