// __builtin_popcount(x) broj bitova
// __builtin_popcountll(x)
// __builtin_clz(x) vodece nule
// __builtin_clzll(x)
// __builtin_ctz(x) nule na pocetku
// __builtin_ctzll(x)
// 2000000011
// 2000000033
#include "bits/stdc++.h"
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
#define ld double
#define ll int
#define ull unsigned long long
#define llinf 100000000000000000LL // 10^17
#define iinf 2000000000 // 2*10^9
#define pb push_back
#define popb pop_back
#define fi first
#define sc second
#define endl '\n'
#define pii pair<int,int>
#define pll pair<ll,ll>
#define pld pair<ld,ld>
#define sz(a) int(a.size())
#define all(a) a.begin(),a.end()
#define rall(a) a.begin(),a.end(),greater<int>()
#define getunique(v) {sort(all(v)); v.erase(unique(all(v)), v.end());}
#define pi 3.14159265358979323846
#define here cerr<<"---------------------------\n"
#define ceri(a,l,r) {for(ll i = l;i<=r;i++) cerr<<a[i]<< " ";cerr<<endl;}
#define ceri2(a,l,r,n,m) {for(ll i = l;i<=r;i++){for(ll j = n;j<=m;j++) cerr<<a[i][j]<< " ";cerr<<endl;}}
#define yes cout<<"YES"<<endl
#define no cout<<"NO"<<endl
using namespace std;
using namespace __gnu_pbds;
typedef tree<int,null_type,less<int>,rb_tree_tag,tree_order_statistics_node_update> ordered_set;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
ll rnd(ll l,ll r){
return uniform_int_distribution<ll>(l,r)(rng);
}
void setIO(string inoutname)
{
freopen((inoutname+".in").c_str(),"r",stdin);
freopen((inoutname+".out").c_str(),"w",stdout);
}
#define mod 1
ll gcd(ll a, ll b)
{
if(b==0) return a;
if(a==0) return b;
if(a>=b) return gcd(a%b,b);
return gcd(a,b%a);
}
ll lcm(ll a,ll b){
return (a/gcd(a,b))*b;
}
ll add(ll a,ll b){
a+=b;
if(a<0) a+=mod;
if(a>=mod) a%=mod;
return a;
}
ll mul(ll a,ll b){return(a*b)%mod;}
#define maxn 500005
vector<ll> g[maxn];
ll n,m;
bool vis[maxn];
vector<ll> ans;
ll it[maxn];
void euler(ll u){
while(it[u]<sz(g[u])){
ll s = g[u][it[u]++];
ll j = g[u][it[u]++]>>32LL;
s = s&((1<<32LL)-1);
if(vis[j]) continue;
euler(s);
}
ans.pb(u);
}
void tc(){
ios_base::sync_with_stdio(false);cerr.tie(0);cout.tie(0);cin.tie(0);
cin >> n >> m;
for(ll i = 1;i<=m;i++){
ll x,y; cin >> x >> y;
g[x].pb(y+(i<<32LL));
g[y].pb(x+(i<<32LL));
}
for(ll i = 1;i<=n;i++) if(!vis[i]) euler(i);
fill(vis,vis+n+1,0);
vector<ll> v;
vector<ll> w;
//ceri(ans,0,sz(ans)-1);
for(ll x : ans){
if(vis[x]==1){
while(v.back()!=x){
w.pb(v.back());
v.popb();
}
w.pb(x);
for(ll y : w){
vis[y] = 0;
cout<<y<< " ";
}
cout<<endl;
w.clear();
vis[x] = 1;
}else vis[x] = 1,v.pb(x);
}
}
int main(){
ios_base::sync_with_stdio(false);cerr.tie(0);cout.tie(0);cin.tie(0);
//setIO("lol");
int t; t = 1;
while(t--){
tc();
}
return 0;
}
/*
10 15
1 3
5 1
2 3
9 2
3 4
6 3
4 5
7 4
4 8
5 7
8 5
6 7
7 8
8 10
10 9
*/
