import java.util.*;

public class Solution {

    static Scanner sc = new Scanner(System.in);


    public static ArrayList<Integer> athleticRace(int N,int M,ArrayList<Integer>[] A){
        ArrayList<Integer> result = new ArrayList<>();

        int[] time = new int[M+1];

        for(int i=1;i<=M;i++) {
            time[i] = -1;
        }

        Queue<Integer> q = new LinkedList<>();
        q.add(M);
        time[M] = 0;

        while(!q.isEmpty()) {
            int temp = q.remove();

            for(int i : A[temp]) {
                if(time[i] == -1) {
                    time[i] = time[temp]+1;
                    q.add(i);
                }
            }
        }

        int max_time = 0;
        HashSet<Integer> hs = new HashSet<>();

        for(int i=1;i<=N;i++) {
            hs.add(time[i]);
            if(max_time < time[i]) {
                max_time = time[i];
            }
        }

        if(hs.size() == 1) {
            result.add(-1);
            return result;
        }

        for(int i=1;i<=N;i++) {
            if(max_time == time[i]) {
                result.add(i);
            }
        }

        return result;
    }

    public static void main(String[] args) {
        int N,M;
        N = sc.nextInt();
        M = sc.nextInt();

        ArrayList<Integer>[] A = new ArrayList[M+1];
        for(int i=0;i<=M;i++) {
            A[i] = new ArrayList<>();
        }

        for(int i = 0;i<M-1;i++) {
            int temp1 = sc.nextInt();
            int temp2 = sc.nextInt();

            A[temp1].add(temp2);
            A[temp2].add(temp1);
        }

        ArrayList<Integer> result = athleticRace(N,M,A);

        for(int i : result) {
            System.out.print(i + " ");
        }
        System.out.println();
    }
}