#include<bits/stdc++.h>
#define pb push_back
#define int long long
#define pii pair<int, int>
#define fi first
#define se second
using namespace std;
const int N = 5e5;
bool hack = 0;
int n, m;
vector<pii> adj[N+1], tmp;
bool vis[N+1], used[N+1];
vector<vector<int>> path;
void dfs(int now, int par) {
if (hack) cout << "now: " << now << " par: " << par << endl;
for (auto i: adj[now]) {
if (tmp.back().fi != now) break;
if (i.fi == par || used[i.se]) continue;
if (vis[i.fi]) {
// cycle!!!
vector<int> p;
used[i.se] = 1; // mark edge from now to i.fi as used
p.pb(i.fi); // push nxt node to path
while (tmp.back().fi != i.fi) {
pii t = tmp.back(); tmp.pop_back();
used[t.se] = 1;
vis[t.fi] = 0;
p.pb(t.fi);
}
used[tmp.back().se] = 1;
path.pb(p);
continue;
}
vis[i.fi] = 1;
tmp.pb({i.fi, i.se});
dfs(i.fi, now);
}
}
signed main() {
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
cin >> n >> m;
for (int i=1; i<=m; i++) {
int u, v;
cin >> u >> v;
adj[u].pb({v, i});
adj[v].pb({u, i});
}
for (int i=1; i<=n; i++) {
vis[i] = 1; tmp.pb({i, 0});
if (hack) cout << "tmp size: " << tmp.size() << endl;
dfs(i, 0);
vis[i] = 0;
}
for (auto p: path) {
cout << p.size() << " ";
for (int node: p) cout << node << " ";
cout << "\n";
}
return 0;
}
