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

void dfs(int v, vector<vector<int>>& graph, vector<int>& colors, vector<int>& component) {
	colors[v] = 1;
	for (int& dest : graph[v]) {
		if (colors[dest] == 0) {
			dfs(dest, graph, colors, component);
		}
	}
	colors[v] = 2;
	component.push_back(v + 1);
}

int main() {
	int n, m;
	cin >> n >> m;
	vector<pair<int, int>> graph0(m);
	for (auto& [f, s] : graph0) {
		cin >> f >> s;
		f--;
		s--;
	}
	
	vector<vector<int>> graph(n);
	for (auto& [f, s] : graph0) {
		graph[f].push_back(s);
		graph[s].push_back(f);
	}
	vector<int> colors(n);
	
	vector<vector<int>> components;
	for (int i = 0; i < n; i++) {
		if (colors[i] == 0) {
			vector<int> component;
			dfs(i, graph, colors, component);
			components.emplace_back(component);
		}
	}
	
	cout << components.size() << '\n';
	for (auto& component : components) {
		cout << component.size() << '\n';
		for (auto& item : component) {
			cout << item << ' ';
		}
		cout << '\n';
	}
	
	return 0;
}