#include <fstream>
#include <iostream>
#include <vector>
#include <bitset>

using namespace std;

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

const int nMax = 1 * 100000 + 10;
const int mMax = 5 * 100000 + 10;

struct Node
{
    int next, edge;
};

int n, m;
vector < Node > l[nMax];
vector < int > r;
bitset < mMax > viz;
int grad[nMax];

void Dfs(int node)
{
    while (!l[node].empty())
    {
        int next = l[node].back().next;
        int edge = l[node].back().edge;

        l[node].pop_back();

        if (!viz[edge])
        {
            viz[edge] = 1;
            Dfs(next);
        }
    }

    r.push_back(node);
}

int main()
{
    bool euler = true;

    fin >> n >> m;

    for (int i = 1; i <= m; i++)
    {
        int a, b;

        fin >> a >> b;

        l[a].push_back({b, i});
        l[b].push_back({a, i});
    }

    Dfs(1);

    for (int i = 1; i <= n && euler; i++)
    {
        euler &= !(l[i].size() % 2);
    }
    
    int rSize = r.size() - 1;

    for (int i = 0; i < rSize; i++)
    {
        fout << r[i] << ' ';
    }

    fin.close();
    fout.close();
    return 0;
}