#include <fstream>
#include <iostream>
#include <vector>
#include <bitset>
#include <string.h>
#include <algorithm>
#include <iomanip>
#include <math.h>
#include <time.h>
#include <stdlib.h>
#include <set>
#include <map>
#include <string>
#include <queue>
#include <stack>

using namespace std;

const char infile[] = "ciclueuler.in";
const char outfile[] = "ciclueuler.out";

ifstream fin(infile);
ofstream fout(outfile);

const int MAXN = 100005;
const int oo = 0x3f3f3f3f;

typedef vector<int> Graph[MAXN];
typedef vector<int> :: iterator It;

const inline int min(const int &a, const int &b) { if( a > b ) return b;   return a; }
const inline int max(const int &a, const int &b) { if( a < b ) return b;   return a; }
const inline void Get_min(int &a, const int b)    { if( a > b ) a = b; }
const inline void Get_max(int &a, const int b)    { if( a < b ) a = b; }

const int lim = (1 << 20);
char buff[lim];
int pos;

inline void get(int &x) {
    while(!('0' <= buff[pos] && buff[pos] <= '9'))
        if(++ pos == lim) {
            pos = 0;
            fread(buff, 1, lim, stdin);
        }
    x = 0;
    while('0' <= buff[pos] && buff[pos] <= '9') {
        x = x * 10 + buff[pos] - '0';
        if(++ pos == lim) {
            pos = 0;
            fread(buff, 1, lim, stdin);
        }
    }
}

Graph G;
int N, M;
stack <int> st;

inline void Euler(int stNode) {
    st.push(stNode);
    vector <int> Ans;
    while(!st.empty()) {
        int Node = st.top();
        if(G[Node].size()) {
            int newNode = G[Node].back();
            G[Node].pop_back();
            G[newNode].erase(find(G[newNode].begin(), G[newNode].end(), Node));
            st.push(newNode);
        } else {
            st.pop();
            if(!st.empty())
                Ans.push_back(Node);
        }
    }
    for(It it = Ans.begin(), fin = Ans.end(); it != fin ; ++ it)
        fout << *it << ' ';
    fout << '\n';
}

int main() {
    freopen(infile, "r", stdin);
    get(N);
    get(M);
    for(int i = 1 ; i <= M ; ++ i) {
        int x, y;
        get(x);
        get(y);
        G[x].push_back(y);
        G[y].push_back(x);
    }
    Euler(1);
    fin.close();
    fout.close();
    return 0;
}