import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Main implements Runnable {
    public static void main(String[] args) {
        new Thread(null, new Main(), "", 64 * 1024 * 1024).start();
    }
    public void run() {
        try (Scanner sc = new Scanner(new FileReader("C:\\Users\\kovic\\Desktop\\Common\\src\\input.txt"));
             FileWriter fw = new FileWriter("C:\\Users\\kovic\\Desktop\\Common\\src\\output.txt")) {
            int n, m, first, second, size;
            n = sc.nextInt();
            m = sc.nextInt();
            List<Integer> [] versh = new ArrayList[n];
            for (int i = 0; i < n; ++i){
                versh[i] = new ArrayList<>();
            }
            for (int i = 0; i < m; ++i) {
                first = sc.nextInt();
                second = sc.nextInt();
                versh[first - 1].add(second);
                versh[second - 1].add(first);
            }
            for (int i = 0; i < n; ++i){
                size = versh[i].size();
                fw.write(String.valueOf(size));
                for (int j = 0; j < size; ++j){
                    fw.write(" " + String.valueOf(versh[i].get(j)));
                }
                fw.write('\n');
            }
        } catch (IOException e1) {
            e1.printStackTrace();
        }
    }

}