package graph;

import java.io.*;

import java.util.StringTokenizer;
import java.util.Vector;

public class Euler_Path implements Runnable {

	class Edge {
		int v1;
		int v2;
		boolean was;

		Edge(int v1, int v2) {
			this.v1 = v1;
			this.v2 = v2;
			was = false;
		}
	}

	int n;
	int m;

	Vector<Vector<Edge>> neigh;
	int[] degree;

	int tmp;

	String ans = "";

	void findPath(int v) {
		Vector<Edge> current = neigh.get(v);

		for(int i = 0; i < current.size(); i++) {
			Edge e = current.get(i);

			if(!e.was) {

				e.was = true;
				tmp = (e.v1 == v) ? e.v2 : e.v1;


				findPath(tmp);
			}
		}
		ans += " " + Integer.toString(v);
	}

	public void run() {
		try {
			BufferedReader in = new BufferedReader(new FileReader("input.txt"));
			PrintWriter out = new PrintWriter("output.txt");
			StringTokenizer st = new StringTokenizer(in.readLine());

			n = Integer.parseInt(st.nextToken());

			neigh = new Vector<Vector<Edge>>(n + 1);

			for(int i = 0; i <= n; i++) {
				neigh.add(new Vector<Edge>());
			}

			degree = new int[n + 1];

			int[][] w = new int[n + 1][n + 1];

			int t;
			Edge e;

			for(int i = 1; i <= n; i++) {
				st = new StringTokenizer(in.readLine());

				int count = Integer.parseInt(st.nextToken());

				for(int j = 0; j < count; j++) {
					t = Integer.parseInt(st.nextToken());

					w[i][t]++;
				}
			}

			for(int i = 1; i <= n; i++) {
				for(int j = 1; j <= n; j++) {
					if(w[i][j] > 0) {
						w[i][j]--;
						w[j][i]--;

						e = new Edge(i, j);

						neigh.get(i).add(e);
						neigh.get(j).add(e);

						degree[i]++;
						degree[j]++;
					}
				}
			}

			boolean hasCycle = true;
			boolean hasPath = true;

			int amount = 0;

			for(int i = 1; i <= n; i++) {
				if((degree[i] & 1) != 0) {
					amount++;
					hasCycle = false;
				}
			}

			if(!hasCycle) {
				if (amount != 2) hasPath = false;
			}

			if(hasCycle) {
				findPath(1);
				int len = ans.length() / 2 - 1;

				out.println(len);
				out.print(ans.substring(1));
			} else if(hasPath) {
				int min = 0;

				for(int i = 1; i <= n; i++) {
					if((degree[i] & 1) != 0) {
						min = i;
						break;
					}
				}

				findPath(min);

				int len = ans.length() / 2 - 1;

				out.println(len);
				out.print(ans.substring(1));

			} else out.print("-1");

			in.close();
			out.close();
		} catch(Exception e) {
			e.printStackTrace();
		}
	}

	public static void main(String[] args) {
		new Thread(new Euler_Path()).start();
	}
}