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

vector<int> athleticRace(int N,int M,map<int,vector<int>> &hm){
    vector<int> dist(M+1,-1);

    queue<int> q;
    q.push(M);
    dist[M] =0;

    while(!q.empty()){
        int temp = q.front();
        q.pop();

        for(int i : hm[temp]){
            if(dist[i]==-1){
                dist[i] = dist[temp]+1;
                q.push(i);
            }
        }
    }

    int max_dist = 0;
    set<int> s;
    for(int i=1;i<=N;i++){
        s.insert(dist[i]);
        max_dist = max(max_dist,dist[i]);
    }

    if(s.size()==1){
        return {-1};
    }

    vector<int> result;
    for(int i=1;i<=N;i++){
        if(dist[i] == max_dist){
            result.push_back(i);
        }
    }
    return result;
}

int main()
{
    int N,M;
    cin>>N>>M;

    map<int,vector<int>> hm;

    for(int i=0;i<M-1;i++){
        int a,b;
        cin>>a>>b;

        hm[a].push_back(b);
        hm[b].push_back(a);
    }

    vector<int> res = athleticRace(N,M,hm);

    for(auto i : res){
        cout<<i<<" ";
    }
    cout<<endl;
}