#include <fstream>
#include <vector>
#include <bitset>
using namespace std;
ifstream fin ("ciclueuler.in");
ofstream fout ("ciclueuler.out");
int n,m,i,x,y,k,sol[500005];
vector <pair <int,int>> v[100001];
bitset <500001> viz;
void dfs (int nod)
{
    while (!v[nod].empty ())
    {
        while (!v[nod].empty ()&&viz[v[nod].back ().second])
            v[nod].pop_back ();
        if (!v[nod].empty ())
        {
            int vecin=v[nod].back ().first;
            int poz=v[nod].back ().second;
            v[nod].pop_back ();
            viz[poz]=1;
            dfs (vecin);
        }
    }
    sol[++k]=nod;
}
int main()
{
    fin>>n>>m;
    for (i=1; i<=m; i++)
    {
        fin>>x>>y;
        v[x].push_back (make_pair (y,i));
        v[y].push_back (make_pair (x,i));
    }
    dfs (1);
    for (i=1; i<k; i++)
        fout<<sol[i]<<" ";
    return 0;
}