#include <iostream>
#include <cstdio>
#include <vector>
#include <stack>
using namespace std;

vector<vector<int>> adjl;
vector<int> low;
stack<int> t;
vector<vector<int>> bccs;
int num = 0;

void dfs(int u, int p)
{
	int numu = num++;
	low[u] = numu;
	t.push(u);
	for (auto v: adjl[u]) {
		if (low[v] == -1) {
			dfs(v, u);
		}
		if (v != p) {
			low[u] = min(low[u], low[v]);
		}
	}
	if (p != -1 && low[u] >= numu-1) {
		vector<int> bcc;
		int top;
		do {
			top = t.top();
			t.pop();
			bcc.push_back(top);
		} while (top != u);
		bcc.push_back(p);
		bccs.push_back(bcc);
	}
}

int main()
{
	ios::sync_with_stdio(false);
	freopen("biconex.in", "r", stdin);
	freopen("biconex.out", "w", stdout);
	int n, m;
	cin >> n >> m;
	adjl.resize(n);
	for (int i = 0; i < m; i++) {
		int u, v;
		cin >> u >> v;
		u--, v--;
		adjl[u].push_back(v);
		adjl[v].push_back(u);
	}
	low.assign(n, -1);
	dfs(0, -1);
	printf("%d\n", bccs.size());
	for (auto& bcc: bccs) {
		for (auto u: bcc) {
			printf("%d ", u+1);
		}
		printf("\n");
	}
	return 0;
}