import java.io.File;
import java.io.PrintWriter;
import java.util.*;

public class Main {
	static class edge {
		int a;
		int b;
		edge(int a, int b) {
			this.a = a;
			this.b = b;
		}
	}

	static class way {
		int i;
		LinkedList<Integer> w = new LinkedList<Integer>();

		way(int i) {
			this.i = i;
		}
	}

	static class DisjointSets {
		static Random rnd = new Random();
		int[] p;
		int size;


		void init() {
			for (int i = 0; i < p.length; i++) {
				p[i] = i;
			}
		}

		DisjointSets(int size) {
			p = new int[size];
			this.size = size;
			init();
		}

		void copy(DisjointSets A)
		{
			for (int i = 0; i < size; ++i)
				p[i] = A.p[i];
		}

		int root(int x) {
			if (p[x] != x) {
				p[x] = root(p[x]);
			}
			return p[x];
		}

		void unite(int a, int b) {
			a = root(a);
			b = root(b);
			if (rnd.nextBoolean()) {
				p[a] = b;
			} else {
				p[b] = a;
			}
		}
	}

	static boolean checkA(int a, int b, DisjointSets ds) {
		if (ds.root(a) == ds.root(b))
			return false;
		return true;
	}

	public static void main(String args[]) {
		try {
			Scanner in = new Scanner(new File("multispan.in"));
			PrintWriter out = new PrintWriter(new File("multispan.out"));
			int m, n;
			n = in.nextInt();
			m = in.nextInt();
			int a, b;
			int[] I = new int[m+1];
			edge[] edges = new edge[m];
			for (int i = 0; i < m; ++i) {
				a = in.nextInt() - 1;
				b = in.nextInt() - 1;
				edges[i] = new edge(a, b);
			}
			int k = 1;
			int size = 0;
			while (true) {
				if (k*(n-1) == size){
					k++;
				}
				LinkedList<Integer> []Ij = new LinkedList[k+1];
				int []A = new int[m];
				for (int i = 0; i <= k; ++i){
					Ij[i] = new LinkedList<Integer>();
				}
				for (int i = 0; i < m; ++i)
				{
					Ij[I[i]].add(i);
				}
				for (int j = 1; j<=k; ++j){
					DisjointSets ds = new DisjointSets(n);
					for (Integer i : Ij[j]){
						ds.unite(edges[i].a, edges[i].b);
					}
					for (int i = 0; i < m; ++i){
						if (checkA(edges[i].a, edges[i].b, ds)){
							A[i] = j;
						}
					}
				}
				boolean add = false;
				for (int i = 0; i < m; ++i){
					if ((A[i] != 0) && (I[i] == 0)){
						I[i] = A[i];
						add = true;
						size++;
						break;
					}
				}
				if (add){
					continue;
				}

				Queue<way> bfs = new LinkedList<way>();
				boolean[] bfc = new boolean[m];

				for (int i = 0; i < m; ++i) {
					if (A[i] != 0) {
						way d = new way(i);
						d.w.add(i);
						bfs.add(d);
						bfc[i] = true;
					}
				}

				way p = new way(-1);
				boolean end = false;
				while (!bfs.isEmpty()) {
					p = bfs.poll();
					if (I[p.i] == 0){
						end = true;
						break;
					}
					DisjointSets ds = new DisjointSets(n);
					for (Integer j : Ij[I[p.i]]){
						if (j != p.i){
							ds.unite(edges[j].a, edges[j].b);
						}
					}
					for (int i =0; i < m; ++i){
						if (!bfc[i]){
							if (checkA(edges[i].a, edges[i].b, ds)){
								way d = new way(i);
								d.w = (LinkedList<Integer>) p.w.clone();
								d.w.add(i);
								bfs.add(d);
								bfc[i] = true;
							}
						}
					}
				}
				if (!end)
					break;
				int first = p.w.pollFirst();
				int newPos = I[first];
				I[first] = A[first];
				for (Integer i : p.w) {
					first = I[i];
					I[i] = newPos;
					newPos = first;
				}
				size++;
			}

			LinkedList<Integer> []Ij = new LinkedList[k+1];
			for (int i = 0; i <= k; ++i){
				Ij[i] = new LinkedList<Integer>();
			}
			for (int i = 0; i < m; ++i)
			{
				Ij[I[i]].add(i);
			}
			if (k*(n-1) != size){
				k--;
			}
			out.println(k);
			for (int j = 1; j <= k; j++){
				for (Integer i : Ij[j]) {
					out.print((i + 1) + " ");
				}
				out.println();
			}
			out.close();
		} catch (Exception e) {
			System.out.print(e);
		}
	}
}