#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef long double ld;
typedef complex<ld> cd;
typedef pair<int, int> pi;
typedef pair<ll,ll> pl;
typedef pair<ld,ld> pd;
typedef vector<int> vi;
typedef vector<ld> vd;
typedef vector<ll> vl;
typedef vector<pi> vpi;
typedef vector<pl> vpl;
typedef vector<cd> vcd;
template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag,tree_order_statistics_node_update>;
#define FOR(i, a, b) for (int i=a; i<(b); i++)
#define F0R(i, a) for (int i=0; i<(a); i++)
#define FORd(i,a,b) for (int i = (b)-1; i >= a; i--)
#define F0Rd(i,a) for (int i = (a)-1; i >= 0; i--)
#define sz(x) (int)(x).size()
#define mp make_pair
#define pb push_back
#define f first
#define s second
#define lb lower_bound
#define ub upper_bound
#define all(x) x.begin(), x.end()
const int MOD = 1000000007;
const ll INF = 1e18;
const int MX = 500001;
int n,m, nex[MX];
vector<array<int,3>> adj[MX];
void addEdge(int x, int y) {
int X = sz(adj[x]), Y = sz(adj[y]);
adj[x].pb({y,Y,0}), adj[y].pb({x,X,0});
}
vi v;
bool oc[MX];
void dfs(int x) {
while (nex[x] < sz(adj[x])) {
if (adj[x][nex[x]][2]) {
nex[x] ++;
continue;
}
adj[x][nex[x]][2] = 1;
int y = adj[x][nex[x]][0];
adj[y][adj[x][nex[x]][1]][2] = 1;
nex[x] ++;
dfs(y);
}
if (oc[x]) {
vi V;
while (v.back() != x) {
V.pb(v.back());
oc[v.back()] = 0;
v.pop_back();
}
V.pb(v.back());
oc[v.back()] = 0;
v.pop_back();
for (int i: V) cout << i << " ";
cout << "\n";
}
v.pb(x); oc[x] = 1; // cout << x << "\n";
}
int main() {
ios_base::sync_with_stdio(0); cin.tie(0);
cin >> n >> m;
F0R(i,m) {
int u,v; cin >> u >> v;
addEdge(u,v);
}
dfs(1);
/*for (int i: v) cout << i << " ";
cout << "\n";
cout << sz(v) << "\n";*/
}
/* Look for:
* the exact constraints (multiple sets are too slow for n=10^6 :( )
* special cases (n=1?)
* overflow (ll vs int?)
* array bounds
*/
