#include <bits/stdc++.h>

using namespace std;

int n, m;
vector <int> graf[100005], rez;

void euler(int start)
{
    vector <int> stiva;
    vector <int>::iterator it;
    stiva.push_back(start);
    while (!stiva.empty())
    {
        int nod = stiva.back();
        if (graf[nod].empty())
        {
            stiva.pop_back();
            rez.push_back(nod);
            continue;
        }
        stiva.push_back(graf[nod].back());
        int nod1 = graf[nod].back();
        graf[nod].pop_back();
        for (it = graf[nod1].begin(); it != graf[nod1].end(); it++)
            if (*it == nod)
            {*it = graf[nod1].back(); graf[nod1].pop_back(); break;}
    }
}

int main()
{
    freopen("ciclueuler.in", "r", stdin);
    freopen("ciclueuler.out", "w", stdout);
    scanf("%d %d", &n, &m);
    for (int i = 1, a, b; i <= n; i++)
        scanf("%d %d", &a, &b),
        graf[a].push_back(b),
        graf[b].push_back(a);
    euler(1);
    rez.pop_back();
    for (const auto &it : rez)
        printf("%d ", it);
}