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

#define SZ(a) (int)a.size()
#define ALL(a) a.begin(), a.end()
#define FOR(i, a, b) for (int i = (a); i<(b); ++i)
#define RFOR(i, b, a) for (int i = (b)-1; i>=(a); --i)
#define MP make_pair
#define PB push_back
#define F first
#define S second
#define FILL(a, b) memset(a, b, sizeof(a))

typedef long long LL;
typedef pair<int, int> PII;
typedef vector<int> VI;

const int MAX = 1 << 18;

vector<int> g[MAX];
bool used[MAX];
vector<int> ans;

void dfs(int v) {
	used[v] = true;
	ans.push_back(v);
	for (int u : g[v]) {
		if (!used[u]) {
			used[u] = true;
			for (int w : g[u]) {
				if (!used[w]) {
					dfs(w);
				}
			}
			ans.push_back(u);
		}
	}
}

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0);
	int n, m;
	cin >> n >> m;
	FOR(i, 0, m) {
		int u, v;
		cin >> u >> v;
		u--;
		v--;
		g[u].push_back(v);
		g[v].push_back(u);
	}
	dfs(0);
	for (int v : ans) {
		cout << v + 1 << " ";
	}
	cout << "\n";
	return 0;
}