t111540

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.StringTokenizer;

public class t111540 {
    static LinkedList<Integer> stack = new LinkedList<>();
    static ArrayList<Integer>[] list;
    static int[] visited;
    static ArrayList<ArrayList<Integer>> res;
    static int cur;

    static void dfs(int vertex, int colour) {
        stack.addFirst(vertex);
        visited[vertex] = colour;
        while(stack.size()!=0) {
            cur = stack.removeFirst();
            res.get(colour-1).add(cur+1);
            for(int i: list[cur]) {
                if(visited[i] == 0) {
                    stack.addFirst(i);
                    visited[i] = colour;
                }
            }
        }
    }


    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st = new StringTokenizer(br.readLine());
        int N = Integer.parseInt(st.nextToken());
        int M = Integer.parseInt(st.nextToken());
        int a, b;
        int colour = 1;
        visited = new int[N];
        list = new ArrayList[N];
        res = new ArrayList<>();
        for (int i = 0; i < N; i++) {
            list[i] = new ArrayList<>();
        }

        for (int i = 0; i < M; i++) {
            st = new StringTokenizer(br.readLine());
            a = Integer.parseInt(st.nextToken());
            b = Integer.parseInt(st.nextToken());
            list[a-1].add(b-1);
            list[b-1].add(a-1);
        }

        for (int i = 0; i < N; i++) {
            if(visited[i] == 0) {
                res.add(new ArrayList<>());
                dfs(i, colour);
                colour++;
            }
        }

        System.out.println(colour-1);
        for (int i = 0; i < res.size(); i++) {
            System.out.println(res.get(i).size());
            for (int j = 0; j < res.get(i).size(); j++) {
                System.out.print(res.get(i).get(j) + " ");
            }
            System.out.println();
        }
    }
}