#include <fstream>
#include <vector>
#include <algorithm>
#include <stack>

#define input "ciclueuler.in"
#define output "ciclueuler.out"
#define NMAX 100005

using namespace std;

ifstream in(input);
ofstream out(output);

struct p
{
	int x, y;
};
vector < int > muchii[NMAX];
vector < int > sol;
stack < int > stiva;
int N, M;
bool uz[5 * NMAX];

bool Sort_Method(p a, p b)
{
	if (a.x != b.x) return a.x < b.x;
	return a.y < b.y;
}

void Read_Data()
{
	in >> N >> M;
	for (int i = 1; i <= M; i++)
	{
		int x, y;
		in >> x >> y;
		muchii[x].push_back(y);
		muchii[y].push_back(x);
	}
	for (int i = 1; i <= N; i++)
		sort(muchii[i].begin(), muchii[i].end());
}

int B_S(int nod, int v)
{
	int st = 0, dr = muchii[nod].size() - 1, poz = -1;
	while (st <= dr)
	{
		int mid = (st + dr) / 2;
		if (muchii[nod][mid] == v)
		{
			poz = mid; break;
		}
		else if (muchii[nod][mid] > v) dr = mid - 1;
		else st = mid + 1;
	}
	return poz;
}

void Solve()
{
	stiva.push(1);
	while (!stiva.empty())
	{
		int nod = stiva.top();
		out << nod << "\n";
		if (muchii[nod].size())
		{
			int new_nod = muchii[nod].back();
			muchii[nod].pop_back();
			// Find nod in new_nod muchii
			int poz = B_S(new_nod, nod);
			muchii[new_nod].erase(muchii[new_nod].begin() + poz);
			stiva.push(new_nod);
		}
		else
		{
			stiva.pop();
			sol.push_back(nod);
		}
	}
	for (unsigned i = 0; i < sol.size() - 1; i++)
		out << sol[i] << " ";
}

int main()
{
	Read_Data();
	Solve();
	return 0;
}