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

int main() {
	int n;
	cin >> n;

	vector<vector<int>> csucsok(n, vector<int>());
	vector<int> fok(n, 0);
	for(int i = 0; i < n; i++){
		while(1){
			int a;
			cin >> a;

			if(a == 0) break;

			a--;
			csucsok[i].push_back(a);
			fok[i]++;
		}
	}

	vector<bool> kettes(n, 0);
	int db = 0;

	while(1){
		bool van = 0;

		for(int i = 0; i < n; i++){
			if(fok[i] >= 2){
				van = 1;

				if(kettes[i]){
					kettes[i] = 0;
					db--;
				} else{
					kettes[i] = 1;
					db++;
				}

				for(int x : csucsok[i]){
                    if(kettes[x] == kettes[i]){
                        fok[i]++;
                        fok[x]++;
                    } else{
                        fok[i]--;
                        fok[x]--;
                    }
				}

				break;
			}
		}

		if(!van){
			break;
		}
	}

	cout << db << "\n";
	for(int i = 0; i < n; i++){
		if(kettes[i]){
			cout << i + 1 << " ";
		}
	}
	cout << "\n";
}