#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
template<typename T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef long long int ll;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL)
#define pb push_back
#define endl '\n'
#define sz(a) (int)a.size()
#define setbits(x) __builtin_popcountll(x)
#define ff first
#define ss second
#define conts continue
#define ceil2(x,y) ((x+y-1)/(y))
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define yes cout << "Yes" << endl
#define no cout << "No" << endl
#define rep(i,n) for(int i = 0; i < n; ++i)
#define rep1(i,n) for(int i = 1; i <= n; ++i)
#define rev(i,s,e) for(int i = s; i >= e; --i)
#define trav(i,a) for(auto &i : a)
template<typename T>
void amin(T &a, T b) {
a = min(a,b);
}
template<typename T>
void amax(T &a, T b) {
a = max(a,b);
}
#ifdef LOCAL
#include "debug.h"
#else
#define debug(x) 42
#endif
/*
refs:
https://github.com/dolphingarlic/CompetitiveProgramming/blob/master/Baltic/Baltic%2014-postmen.cpp
https://codeforces.com/blog/entry/49035 (algorithm to find euler circuit)
*/
const int MOD = 1e9 + 7;
const int N = 5e5 + 5;
const int inf1 = int(1e9) + 5;
const ll inf2 = ll(1e18) + 5;
set<pii> adj[N];
vector<int> ord;
void dfs1(int u){
while(!adj[u].empty()){
auto [v,id] = *adj[u].begin();
adj[u].erase(adj[u].begin());
adj[v].erase({u,id});
dfs1(v);
}
ord.pb(u);
}
void solve(int test_case)
{
int n,m; cin >> n >> m;
rep1(i,m){
int u,v; cin >> u >> v;
adj[u].insert({v,i}), adj[v].insert({u,i});
}
dfs1(1);
ord.pop_back();
vector<vector<int>> ans;
vector<int> curr;
vector<bool> there(n+5);
trav(u,ord){
if(!there[u]){
curr.pb(u);
there[u] = 1;
conts;
}
vector<int> cyc;
cyc.pb(u);
while(curr.back() != u){
cyc.pb(curr.back());
there[curr.back()] = 0;
curr.pop_back();
}
reverse(all(cyc));
ans.pb(cyc);
}
ans.pb(curr);
trav(cyc,ans){
trav(u,cyc){
cout << u << " ";
}
cout << endl;
}
}
int main()
{
fastio;
int t = 1;
// cin >> t;
rep1(i, t) {
solve(i);
}
return 0;
}
