#include <bits/stdc++.h>
#define ll long long
#define pb push_back
#define pf push_front
#define MOD 1000000007
#define MAX 100005

using namespace std;

ifstream fin("ciclueuler.in");
ofstream fout("ciclueuler.out");


vector < pair < int, int > > v[MAX];
vector < int > R;
stack < int > s;
bitset < 5 * MAX > viz;

int main()
{
    int n, m, x, y, i, nod;

    fin >> n >> m;
    for(i = 1; i <= m; ++i)
    {
        fin >> x >> y;
        v[x].pb({y, i});
        v[y].pb({x, i});
    }
    for(int i = 1; i <= n; i++) if(v[i].size() % 2 == 1) i = n + 1;
    if(i != n + 2)
    {
        s.push(1);
        while(s.empty() == 0)
        {
            nod = s.top();
            x = v[nod][v[nod].size()-1].first, y = v[nod][v[nod].size()-1].second;

            if(v[nod].empty() == 0)
            {
                if(viz[y] == 0) viz[y] = 1, s.push(x);
                v[nod].pop_back();
            }
            else
            {
                s.pop();
                R.pb(nod);
            }
        }

        R.pop_back();
        for(auto it:R) fout << it << ' ';
    }


    return 0;
}