#include <bits/stdc++.h>
using namespace std;
#define _ <<" "<<
#define sz(x) ((int) (x).size())
typedef pair<int, int> pii;
typedef long long ll;
const int maxn = 2e5 + 5;


int n, m;
vector<int> G[maxn];
int vis[maxn];

vector<int> ans;

void dfs(int x, int t) {
    vis[x] = 1;
    // cout << x << endl;
    if (!t) {
        ans.push_back(x);
    }
    for (auto v : G[x]) if (!vis[v]) {
        if (t == 0) dfs(v, 1);
        else dfs(v, 0);
    }
    if (t) ans.push_back(x);
}

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cin >> n >> m;
    for (int i = 1;i <= m; ++i) {
        int x,y; cin >> x >> y;
        G[x].push_back(y);
        G[y].push_back(x);
    }
    dfs(1, 0);
    for (auto x : ans) cout << x << " ";
    cout << '\n';
    return 0;
}