#include <cstdio>
#include <vector>
#include <stack>
using namespace std;
const int NMAX = 100505;

int N, M, parent[NMAX];
vector<vector<int>> graph;

int low[NMAX], lvl[NMAX];
bool visited[NMAX];
stack<pair<int, int>> edges;
vector<vector<int>> comps;
int nodeToComp[NMAX];

void read() {
	scanf("%d%d", &N, &M);
	graph.assign(N + 1, vector<int>());
	int x, y;
	for (int edgeIdx = 0; edgeIdx < M; edgeIdx++) {
		scanf("%d%d", &x, &y);
		graph[x].push_back(y);
		graph[y].push_back(x);
	}
}

void addNodeToLatestComp(int node, int compsNo, vector<int>& newComp) {
	if (nodeToComp[node] != compsNo) {
		nodeToComp[node] = compsNo;
		newComp.push_back(node);
	}
}

void addEdgeToLatestComp(pair<int, int>& edge, int compsNo, vector<int>& newComp) {
	addNodeToLatestComp(edge.first, compsNo, newComp);
	addNodeToLatestComp(edge.second, compsNo, newComp);
}
 
void dfs(int node) {
	visited[node] = true;
	low[node] = lvl[node];
	for (auto& neighbour : graph[node]) {
		if (!visited[neighbour]) {
			parent[neighbour] = node;
			edges.push({node, neighbour});
			lvl[neighbour] = lvl[node] + 1;
			dfs(neighbour);

			if (low[neighbour] >= lvl[node]) {
				vector<int> newComp;
				while (!edges.empty()) {
					pair<int, int> edge = edges.top();
					edges.pop();
					addEdgeToLatestComp(edge, (int) comps.size() + 1, newComp);
					if (edge.first == node && edge.second == neighbour) {
						break;
					}
				}
				comps.push_back(newComp);
			}
			low[node] = min(low[node], low[neighbour]);
		} else if (parent[node] != neighbour) {
			low[node] = min(low[node], low[neighbour]);
		}
	}
}

void solve() {
	for (int node = 1; node <= N; node++) {
		if (!visited[node]) {
			dfs(node);
		}
	}

	printf("%d\n", (int) comps.size());
	for (auto comp : comps) {
		for (auto node : comp) {
			printf("%d ", node);
		}
		printf("\n");
	}
}

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

	read();
	solve();
	return 0;
}