#include <bits/stdc++.h>

using namespace std;

ifstream f("biconex.in");
ofstream g("biconex.out");

stack <pair <int, int>> st;

vector <unordered_set <int>> bcc;
vector <int> gr[100001];

int tin[100001], low[10001];
int N, M;

void Read(){
	f >> N >> M;
	while(M--){
		int x, y;
		f >> x >> y;
		gr[x].emplace_back(y);
		gr[y].emplace_back(x);
	}
}

void find_bcc(int x, int y){
	unordered_set <int> con;
	int tx, ty;

	pair <int, int> tp, edge{x, y};

	while(true){
		tx = st.top().first, ty = st.top().second;
		tp = st.top();
		st.pop();
		con.insert(tx), con.insert(ty);
		if(tp == edge)
			break;
	}

	bcc.emplace_back(con);
}

void dfs(int v = 1, int p = 0){
	tin[v] = low[v] = tin[p] + 1;

	for(int to : gr[v]){
		if(to == p) continue;

		if(!tin[to]){
			st.push({v, to});
			dfs(to, v);
			low[v] = min(low[v], low[to]);

			if(low[to] >= tin[v])
				find_bcc(v, to);
		}
		else low[v] = min(low[v], tin[to]);
	}
}


void Print_bcc(){
	g << bcc.size() << "\n";
	for(int i = 0;i < (int)bcc.size();i++){
		for(int x : bcc[i])
			g << x << " ";
		g << "\n";
	}
}


int main(){
	Read();
	dfs();
	Print_bcc();
}