#include <fstream>
#include <vector>
using namespace std;

const int N = 1 + 1e5, M = 1 + 5e5;

class Stack{
    int v[M];

public:
    Stack(){
        v[0] = 0;
    }

    void push(int x){
        v[ ++v[0] ] = x;
    }

    int pop(){
        return v[ --v[0] ];
    }

    int top(){
        return v[ v[0] ];
    }

    bool isEmpty(){
        return v[0] == 0;
    }
};

struct Muchie{
    int x, index;
    Muchie(int x, int i) : x(x), index(i) {};
};

vector<Muchie> graph[N];
bool usedEdge[N];
Stack S;
int n;

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

void readGraph(){
    int m, x, y;

    in >> n >> m;
    for (int i = 1 ; i <= m ; i++){
        in >> x >> y;
        graph[x].push_back( Muchie(y, i) );
        graph[y].push_back( Muchie(x, i) );
    }
}

void euler(int x){
    while ( !graph[x].empty() && ( !graph[x].back().x || usedEdge[ graph[x].back().index ] ) )
        graph[x].pop_back();
    if (!graph[x].empty()){
        usedEdge[ graph[x].back().index ] = true;
        int y = graph[x].back().x;
        graph[x].pop_back();
        euler(y);
        out << x << " ";
    }
}

int main(){
    readGraph();
    euler(1);
    return 0;
}