#include <iostream>
#include <vector>
#include<bitset>
using namespace std;
typedef vector<int> vi;
typedef pair<int,int> ii;
typedef vector<ii> vii;
typedef vector<vii> vvi;
bitset<1000000> mp;
vvi g;
vi path;
vi vis;
void dfs(int u){
path.push_back(u);
if(vis[u]==true){
int x = u;
int size=(int)path.size()-1;
do{
cout<<path[size]<<" ";
vis[path[size]]=false;
path.pop_back();
size--;
}while(path[size]!=x && size>0);
cout<<'\n';
}
vis[u]=true;
for(auto v: g[u]){
vis[u]=true;
if(mp[v.second]!=1){
mp[v.second]=1;
dfs(v.first);
}
}
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
int n,m;
cin>>n>>m;
g.resize(n+1,vii());
vis.resize(n+1,0);
for(int i=0; i<m; i++){
int a,b;
cin>>a>>b;
if(a>b) swap(a,b);
mp[i] = 0;
g[a].push_back({b,i});
g[b].push_back({a,i});
}
dfs(1);
}
