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package alg;

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;

/**
 *
 * @author chlupnoha
 */
public class Main {

    static ArrayList<ArrayList<Integer>> list = new ArrayList<>();
    static ArrayList<int[]> result = new ArrayList<>();

    public static void main(String[] args) throws FileNotFoundException, IOException {
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
//        BufferedReader in = new BufferedReader(new FileReader("/home/chlupnoha/Plocha/pub/pub04.in"));

        int N, M;
        String[] line = in.readLine().trim().split(" ");
        N = Integer.parseInt(line[0]);
        M = Integer.parseInt(line[1]);

        for (int i = 0; i < N; i++) {
            list.add(new ArrayList());
        }

        String[] s;
        int a1, a2;
        for (int i = 0; i < M; i++) {
            ArrayList tempList = new ArrayList();

            s = in.readLine().split(" ");
            a1 = Integer.parseInt(s[0]);
            a2 = Integer.parseInt(s[1]);

            tempList = list.get(a1);
            tempList.add(a2);
            list.set(a1, tempList);

            tempList = list.get(a2);
            tempList.add(a1);
            list.set(a2, tempList);
        }

//        printInput();
        ArrayList<Integer> tmp;
        for (int i = 0; i < N; i++) {
            tmp = list.get(i);
            for (int q : tmp) {
                if (q > i) {
                    findStar(i, q, 1, 1, new int[]{i, q, -1, -1, -1});
                }
            }
        }
        printRes();
//        System.out.println(result.size());
    }

    public static void printInput() {
        int count = 0;
        for (ArrayList<Integer> array : list) {
            System.out.print("c " + count + ": ");
            for (Integer i : array) {
                System.out.print(i + " ");
            }
            System.out.println("");
            count++;
        }
    }

    static int problem = 0;

    public static void findStar(int starting, int curr, int dioda, int pos, int[] visited) {
        problem++;
        System.out.print(problem + " starting:" + starting + " actual:" + curr + " pos: " + pos + " visited: ");
        for (Integer v : visited) {
            System.out.print(v + " ");
        }
        System.out.println("");

        visited[pos] = curr;

        //princip diody na duplikace by Evzen
        int down = Integer.MAX_VALUE;
        if (dioda > 1) {
            down = curr;
        }
        for (int hrana : list.get(curr)) {
            if (hrana > starting && hrana < down) {

                int count = neighbor(visited, hrana, pos);

                if (pos < 3 && count > 0) {
                    continue;
                }
                if (pos == 3 && count != 1) {
                    continue;
                }

                if (pos == 3) {
                    visited[pos + 1] = hrana;
                    if (list.get(starting).contains(hrana)) {
                        int[] nove = Arrays.copyOf(visited, visited.length);
                        Arrays.sort(nove);
                        Arrays.sort(nove);
                        result.add(nove);
//                        System.out.println("add");
                    }
                    visited[pos + 1] = 0;
                } else {
                    if (hrana > curr) {
                        dioda++;
                    }

//                    int[] nove = new int[5];
//                    System.arraycopy(visited, 0, nove, 0, pos + 1);
//                    nove[pos + 1] = hrana;
                    findStar(starting, hrana, dioda, pos + 1, visited);

                    if (hrana > curr) {
                        dioda--;
                    }
                }
            }
        }
        visited[pos] = 0;

    }

    public static int neighbor(int[] vis, int hrana, int pos) {
        int count = 0;
        for (int i = 0; i < pos; i++) {
            if (list.get(hrana).contains(vis[i])) {
                count++;
            }
        }
        return count;
    }

    public static void printRes() {
        Collections.sort(result, new ArrayComparator());
        for (int[] array : result) {
            for (Integer i : array) {
                System.out.print(i + " ");
            }
            System.out.println("");
        }
    }

    static class ArrayComparator implements Comparator<int[]> {

        @Override
        public int compare(int[] t, int[] t1) {
            for (int i = 0; i < 5; i++) {
                if (t[i] < t1[i]) {
                    return -1;
                }
                if (t[i] > t1[i]) {
                    return 1;
                }
            }
            return 0;
        }
    }

}