// UUID: 77eaf51d-a8db-415a-b5f9-72849b898c2f
#include <bits/stdc++.h>
using namespace std;

int main() {
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	int n;
	cin >> n;
	vector<array<int, 4>> opps(n);
	vector<int> numOpps(n);
	for(int i=0;i<n;i++){
		for(int j=0;j<4;j++){
			cin >> opps[i][j];
			opps[i][j]--;
			if(opps[i][j]==-1){
				numOpps[i]=j;
				break;
			}
		}
	}
	vector<int> group(n);
	bool finished=false;
	while(!finished){
		finished=true;
		for(int i=0;i<n;i++){
			int oppCnt=0;
			for(int j=0;j<numOpps[i];j++){
				oppCnt+=(group[opps[i][j]]==group[i]);
			}
			if(1<oppCnt){
				finished=false;
				group[i]=1-group[i];
			}
		}
	}
	int ans=0;
	for(bool x : group) ans+=x;
	cout << ans << '\n';
	for(int i=0;i<n;i++) if(1==group[i]) cout << i+1 << ' ';
}