// Success consists of going from failure to failure without loss of enthusiasm
#include <bits/stdc++.h>
using namespace std;
#define nl '\n'
#define pb push_back
#define pf push_front
#define mp make_pair
#define f first
#define s second
#define sz(x) int(x.size())
template<class T> using V = vector<T>;
using pi = pair<int, int>;
using vi = V<int>;
using vpi = V<pi>;
using ll = long long;
using pl = pair<ll, ll>;
using vpl = V<pl>;
using vl = V<ll>;
using db = long double;
template<class T> using pq = priority_queue<T, V<T>, greater<T>>;
const int MOD = 1e9 + 7;
const ll INFL = ll(1e17);
const int LG = 18;
int main() {
cin.tie(0)->sync_with_stdio(0);
int N, M; cin >> N >> M;
V<vpi> adj(N); vi E(M);
vi cur(N, 0);
for(int i = 0; i < M; i++) {
int u, v; cin >> u >> v; --u, --v;
adj[u].pb(mp(v, i));
adj[v].pb(mp(u, i));
}
V<vi> ans;
vi stk; vi vis(N);
function<void(int)> dfs = [&](int u) {
stk.pb(u); vis[u] = 1;
// cerr << "ENTER " << u << endl;
// cerr << "STK ";
// for(auto& x : stk) cerr << x << " ";
// cerr << endl;
bool done = 1;
while(cur[u] < sz(adj[u])) {
int v, i; tie(v, i) = adj[u][cur[u]++];
if (E[i]) continue;
done = 0; E[i] = 1;
if (vis[v]) {
vi cyc;
for(int x = -1; x != v; ) {
cyc.pb(x = stk.back()); stk.pop_back();
vis[x] = 0;
}
// cerr << "CYC ";
// for(auto& x : cyc) cerr << x << " ";
// cerr << nl;
ans.pb(cyc); stk.pb(v);
return;
}
dfs(v);
if (stk.back() != u) return;
}
if (done) {
// cerr << "DONE " << u << endl;
stk.pop_back(); vis[u] = -1;
}
// cerr << "LEFT " << u << endl;
};
for(int i = 0; i < N; i++) {
// cerr << i << " => " << vis[i] << endl;
if (vis[i] != -1) dfs(i);
}
for(auto& v : ans) {
for(auto& x : v) cout << x + 1 << " ";
cout << nl;
}
exit(0-0);
}
