#include <fstream>
#include<vector>
using namespace std;
ofstream g("biconex.out");
vector <vector <int> > graph;
int n,m;
vector <bool> visited;
vector <int> tata;
/*void DFS(int v)
{
    viz[v]=true;
    for(int j=0;j<graph[v].size();j++)
    {
        if(viz[graph[v][j]]==false)
        {
            tata[graph[v][j]]=v;
            DFS(graph[v][j]);
        }
        else
        {
            if(tata[v]!=graph[v][j])
            {
                int x=tata[v];
                g<<v<<" ";
                while(x!=graph[v][j])
                {
                    g<<x<<" ";
                    int p=tata[x];
                    x=p;
                }
                g<<graph[v][j]<<" "<<v;
                break;
            }
        }
    }
}*/
void dfs(int vertex)
{
    if(vertex<0||vertex>n-1)
        return;
    vector<int> s;
    int element;
    unsigned int i;
    bool found;
    s.push_back(vertex);
    visited[vertex]=true;
    while(!s.empty())
    {
        element=s.back();
        found=false;
        for(i=0;i<graph[element].size()&&!found;i++)
        {
            if(!visited[graph[element][i]])
            {
                tata[graph[element][i]]=element;
                found=true;
            }
        }
        if(found)
        {
            i--;
            s.push_back(graph[element][i]);
            visited[graph[element][i]]=true;

        }
        else
        {
            i--;
            if(tata[element]!=graph[element][i])
            {
                int x=tata[element];
                g<<element<<" ";
                while(x!=graph[element][i])
                {
                    g<<x<<" ";
                    int p=tata[x];
                    x=p;
                }
                g<<graph[element][i]<<" "<<element;

            }
            //for(int i=0;i<n;i++)
               // tata[i]=i;
            s.pop_back();
        }
    }
}
int main()
{
    ifstream f("biconex.in");
    f>>n>>m;
    graph.resize(n);
    tata.resize(n);
    for(int i=0;i<n;i++)
        tata[i]=i;
    visited.resize(n,false);
    int x,y;
    for(int i=0; i<m;i++)
    {
        f>>x>>y;
        x--;
        y--;
        graph[x].push_back(y);
        graph[y].push_back(x);
    }
    for(int i=0;visited.size()&&i<n;i++)
    {
        if(visited[i]==false)
            dfs(i);
    }
    f.close();
    g.close();
    return 0;
}