// UUID: a7ba993c-307c-424e-bb5d-699ac2006b35
#include <bits/stdc++.h>
using namespace std;

int main() {
	int n;
	cin >> n;
	vector<array<int, 4>> opps(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) break;
		}
	}
	vector<int> group(n);
	fill(group.begin(), group.end()-n/2, 0);
	fill(group.begin()+n/2, group.end(), 1);
	for(int i=0;i<n;i++){
		int oppCnt=0;
		for(int j=0;j<4;j++){
			if(opps[i][j]==-1) break;
			oppCnt+=(group[opps[i][j]]==group[i]);
		}
		if(1<oppCnt) 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 << ' ';
}