// Oh damn, cann't you see I'm fine?

#include <bits/stdc++.h>
using namespace std;

#define endl '\n'

const int N = 1e5 + 5;

#define x first
#define y second

int n, m;
vector <int> g[N];

int cnt = 1;
bool mark[N];
int seen[N];
int lowest_seen[N];

void dfs(int u, int p) {
	lowest_seen[u] = seen[u] = cnt++;
	for(int v : g[u]) {
		if(!seen[v]) {
			dfs(v, u);
			if(lowest_seen[v] >= seen[u]) mark[u] = 1;
			lowest_seen[u] = min(lowest_seen[u], lowest_seen[v]);
		}
		else if(v != p) {
			lowest_seen[u] = min(lowest_seen[v], seen[v]);
		}
	}
}

void dfs1(int u) {
	seen[u] = 1;
	for(int v : g[u]) {
		if(!seen[v] && !mark[v]) dfs1(v);
	}
}

set <int> res;
set <int> seen_mark;

void dfs2(int u, int p) {
	if(mark[u]) seen_mark.insert(u);
	res.insert(u);
	if(mark[u]) {
		for(int v : g[u]) {
			if(v == p) continue;
			if(seen[v] == 1) {
				seen[v] = 2;
				dfs2(v, p);
			}
		}
	}
	else {
		for(int v : g[u]) {
			if(v == p) continue;
			if(mark[v]) {
				dfs2(v, p);
			}
			if(seen[v] == 1) {
				seen[v] = 2;
				dfs2(v, p);
			}
		}
	}
}

int main() {
	freopen("biconex.in", "r", stdin);
	freopen("biconex.out", "w", stdout);

	cin >> n >> m;
	for(int i=0; i<m; i++) {
		int x, y;
		cin >> x >> y;
		g[x].push_back(y);
		g[y].push_back(x);
	}
	dfs(1, 0);
	memset(seen, 0, sizeof seen);
	set < set <int> > ans;
	for(int i=1; i<=n; i++) if(mark[i]) {
		dfs1(i);
		seen[i] = 0;
		// seen_mark.clear();
		for(int v : g[i]) {
			if(seen[v] == 1) {
				seen[v] = 2;
				res.clear();
				res.insert(i);
				dfs2(v, i);
				ans.insert(res);
				// cout << i << " " << endl;
				// for(int t : res) cout << t  << " "; cout<<endl;
			}
		}
		for(int v : g[i]) {
			if(mark[v] && !seen_mark.count(v)) {
				res.clear();
				res.insert(i);
				dfs2(v, i);
				ans.insert(res);

				cout << i << " " << endl;
				for(int t : res) cout << t  << " "; cout<<endl;
			}
		}
	}
	cout << ans.size() << endl;
	for(auto con : ans) {
		for(int e : con) cout << e << " ";
		cout << endl;
	}

	return 0;
}