#include <iostream>
#include <cstdio>
#include <vector>
#include <stack>

#define NMAX 100005
#define MMAX 200005

using namespace std;

int N,M,K;
vector<int> graf[NMAX];
vector<int> rez[NMAX];
stack<int> stiva;
int niv[NMAX],sus[NMAX];

void citire()
{
    scanf("%d%d",&N,&M);
    for(int i=1; i<=M; i++)
    {
        int x,y;
        scanf("%d%d",&x,&y);
        graf[x].push_back(y);
        graf[y].push_back(x);
    }
}

void elim(int x)
{
    K++;
    while(stiva.top()!=x)
    {
        rez[K].push_back(stiva.top());
        stiva.pop();
    }
    rez[K].push_back(x);
}

void dfs(int x,int t)
{
    niv[x] = niv[t]+1;
    sus[x] = niv[x];

    for(vector<int>::iterator it = graf[x].begin(); it!=graf[x].end(); it++)
        if(t == *it)
            continue;
        else if(niv[*it] == 0) //nevizitat
        {

            stiva.push(*it);
            dfs(*it,x);
            sus[x] = min(sus[x],sus[*it]);

            if(niv[x] <= sus[*it]) //x punct de articulatie
                elim(x);
        }
        else
            sus[x] =  min(sus[x],niv[*it]);
}

void afisare()
{
    printf("%d\n",K);
    for(int i=1; i<=K; i++)
    {
        for(vector<int>::iterator ii=rez[i].begin(); ii!=rez[i].end(); ii++)
            printf("%d ",*ii);
        printf("\n");
    }
}

int main()
{
    freopen("biconex.in","r",stdin);
    freopen("biconex.out","w",stdout);
    citire();
    stiva.push(1);
    dfs(1,0);
    afisare();


    return 0;
}