import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;

public class ds2 {

	static int[] arrow;

	static int findLeader(int person) {
		if (arrow[person] == person) {
			return person;
		}
		int nextPerson = arrow[person];
		int group = findLeader(nextPerson);
		arrow[person] = group;
		return group;
	}

	static void combine(int person1, int person2) {
		int person1Leader = findLeader(person1);
		int person2Leader = findLeader(person2);
		arrow[person1Leader] = person2Leader;
	}

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		String[] line = br.readLine().split(" ");

		int n = Integer.parseInt(line[0]);
		int m = Integer.parseInt(line[1]);

		// initializing disjoint set
		arrow = new int[n + 6];
		for (int i = 0; i < arrow.length; i++) {
			arrow[i] = i;
		}

		ArrayList<Integer> answer = new ArrayList<Integer>();

		// go through each edge
		for (int i = 0; i < m; i++) {
			line = br.readLine().split(" ");
			int a = Integer.parseInt(line[0]);
			int b = Integer.parseInt(line[1]);

			int aLeader = findLeader(a);
			int bLeader = findLeader(b);
			if (aLeader == bLeader) {
				// skip
			} else {
				answer.add(i);
				combine(a, b);
			}
		}

		// check answer
		if (answer.size() != n - 1) {
			// tree must have n-1
			System.out.println("Disconnected Graph");
		} else {
			for (int edge : answer) {
				System.out.println(edge + 1);
			}
		}
	}

}