#include <bits/stdc++.h>
using namespace std;

using ll = long long;
using ld = long double;
using pll = pair<ll, ll>;
using vll = vector<ll>;
using vld = vector<ld>;
using vpll = vector<pll>;
using vvll = vector<vll>;

vvll graph;
vector<bool> visited;
vll result;

void dfs(ll v, ll depth){
    visited[v] = true;
    if (!(depth % 3)) result.push_back(v);
    for (ll w : graph[v]) if (!visited[w]) dfs(w, depth+1);
    if ((depth % 3)) result.push_back(v);
}

int main(){
    ll n, m;
    cin >> n >> m;
    graph = vvll(n+1,vll{});
    visited = vector<bool>(n+1,false);
    for (int i=0;i<m;i++){
        ll x, y;
        cin >> x >> y;
        graph[x].push_back(y);
        graph[y].push_back(x);
    }
    dfs(1, 0);
    for (ll i : result)
        cout << i << ' ';
    cout << endl;
    return 0;
}