#include <bits/stdc++.h>
#define FAST ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);cerr.tie(0)
#define mp make_pair
#define xx first
#define yy second
#define pb push_back
#define pf push_front
#define popb pop_back
#define popf pop_front
#define all(x) x.begin(),x.end()
#define ff(i,a,b) for (int i = a; i < b; i++)
#define fff(i,a,b) for (int i = a; i <= b; i++)
#define bff(i,a,b) for (int i = b-1; i >= a; i--)
#define bfff(i,a,b) for (int i = b; i >= a; i--)
using namespace std;
long double typedef ld;
unsigned int typedef ui;
long long int typedef li;
pair<int,int> typedef pii;
pair<li,li> typedef pli;
pair<ld,ld> typedef pld;
vector<vector<int>> typedef graph;
unsigned long long int typedef ull;
//const int mod = 998244353;
const int mod = 1000000007;
//Note to self: Check for overflow
vector<vector<int>> ans;
vector<vector<int>> g(500005); //za svaki cvor pamtimo vector indeksa edge-ova
pii ed[500005];
bool potrosen[500005]; //da li je edge vec iskoriscen?
vector<int> put;
bool tvis[500005]; //trenutno posecen?
void dfs(int p)
{
if (tvis[p])
{
while (true)
{
cout<<put.back()<<" ";
bool is_break=(put.back()==p);
tvis[put.back()]=false,put.popb();
if (is_break) break;
}
cout<<"\n";
}
put.pb(p),tvis[p]=true;
while (!g[p].empty())
{
int ind=g[p].back();
g[p].popb();
if (potrosen[ind]) continue;
potrosen[ind]=true;
auto [u,v]=ed[ind];
if (p==u) dfs(v);
else dfs(u);
goto uso;
}
put.popb(),tvis[p]=false;
uso:;
}
int main()
{
FAST;
int n,m; cin>>n>>m;
ff(i,0,m)
{
int u,v; cin>>u>>v;
g[u].pb(i),g[v].pb(i);
ed[i]={u,v};
}
fff(i,1,n) dfs(i);
}
//Note to self: Check for overflow
