#include<fstream>
#include<vector>
#include<list>
#include<stack>

using namespace std;
typedef int var;

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

struct Edge {
    var n, i;
    Edge(var a, var b) : n(a), i(b) {}
};

const var MAXN = 100001;

vector<bool> TAKEN;
vector<Edge> G[MAXN];
var n, m;

void euler(var node, bool first) {

    for(vector<Edge>::iterator it = G[node].begin(); it != G[node].end(); ++it) {
        Edge &e = *it;
        if(!TAKEN[e.i]) {
            TAKEN[e.i] = 1;
            euler(e.n, 0);
            fout<<e.n<<" ";
        }
    }
}

int main() {
    var a, b;
    fin>>n>>m;
    TAKEN.resize(m+1, 0);
    for(var i=1; i<=m; i++) {
        fin>>a>>b;
        G[a].push_back(Edge(b, i));
        G[b].push_back(Edge(a, i));
    }

    euler(1, 1);
    return 0;
}