#include <bits/stdc++.h>
using namespace std;
int used_edges = 0;
vector<int> used;
vector<vector<pair<int, int>>> adj;
vector<int> edgtojun;
vector<bool> vis;
vector<int> sol;
bool dfs(int u, int time, int start = -1, int p = -1) {
if (u == start) {
return true;
}
if (start == -1)
start = u;
if (vis[u] == time)
return false;
vis[u] = time;
for (auto [v, edg] : adj[u]) {
if (!used[edg] && v != p) {
if (dfs(v, time, start, u)) {
used[edg] = 1;
used_edges++;
sol.push_back(u);
return true;
}
}
}
return false;
}
int main() {
int n, m;
cin >> n >> m;
adj.resize(n);
used.resize(m);
edgtojun.resize(m);
for (int i = 0; i < m; i++) {
int u, v;
cin >> u >> v;
u--;
v--;
adj[u].push_back({v, i});
adj[v].push_back({u, i});
edgtojun[i] = u;
}
vis.resize(n, -1);
vector<vector<int>> sols;
for (int i = 0; i < m; i++) {
if (dfs(edgtojun[i], i)) {
reverse(sol.begin(), sol.end());
sols.push_back(sol);
sol.clear();
}
}
for (auto sol : sols) {
for (int idx : sol)
cout << idx + 1 << " ";
cout << "\n";
}
return 0;
}
