#include <iostream>
#include <fstream>
#include <vector>
#include <stack>
#include <unordered_map>

using namespace std;

int N, M;


void euler(vector<vector<int>>& links, vector<int>& from, vector<int>& to, vector<bool>& visits, vector<int>& cycle, int v)
{
	stack<int> nodeStack;
	nodeStack.push(v);

	while (!nodeStack.empty())
	{
		int node = nodeStack.top();

		if(!links[node].empty())
		{
			int edge = links[node].back();
			links[node].pop_back();
			if (!visits[edge])
			{
				visits[edge] = true;
				int destination;
				if (from[edge] != node)
				{
					destination = from[edge];
				}
				else
				{
					destination = to[edge];
				}

				nodeStack.push(destination);
				//euler(links, from, to, visits, cycle, destination);
			}
		}
		else
		{
			nodeStack.pop();
			cycle.push_back(node);
		}
	}
}

int main()
{
	ifstream f("ciclueuler.in");
	ofstream g("ciclueuler.out");
	// Program


	f >> N >> M;
	vector<vector<int>> links(N + 1, vector<int>());
	// links[x] - all the links that have x
	// links[x][1] = p   - p'th link contains x
	vector<int> from(M);
	vector<int> to(M);


	for (int i = 0; i < M; i++)
	{
		int source, destination;
		f >> source >> destination;

		links[source].push_back(i);
		links[destination].push_back(i);
		from[i] = source;
		to[i] = destination;
	}
	vector<int> cycle;
	vector<bool> visits(M);

	euler(links, from, to, visits, cycle, 1);

	auto end = cycle.end() - 1;
	for (auto it = cycle.begin(); it != end; it++)
	{
		g << *it << " ";
	}

	// Exit
	f.close();
	g.close();
	return 0;
}