#include <fstream>
#include <vector>
#include <algorithm>
#include <queue>
using namespace std;
ifstream fin("ciclueuler.in");
ofstream fout("ciclueuler.out");
int n,m,nr,fr[500005];
deque <int> q;
vector <int> sol;
struct numar
{
    int x,i;
};
vector <numar> A[100001];

int main()
{
    fin>>n>>m;
    for(int i=1;i<=m;i++)
    {
        int x,y;
        fin>>x>>y;
        A[x].push_back({y,i});
        A[y].push_back({x,i});

    }
    q.push_back(1);
    while(!q.empty())
    {
        int x=q.back();



        if(!A[x].empty())
        {

            auto y=A[x].back();
            A[x].pop_back();
            if(fr[y.i]==0)
            {
                fr[y.i]=1;
                q.push_back(y.x);

            }


        }

        else{
      q.pop_back();
        sol.push_back(x);}



    }
    for(int i=0;i<sol.size()-1;i++)
       fout<<sol[i]<<" ";




    return 0;
}