#include <iostream>
#include <cstdio>
#include <vector>
#define min(a, b) a<b?a:b
#define N 100005

using namespace std;

vector <int> graf[N], sol[N];
vector <int> :: iterator it;
int viz[N], n, m, nr, niv[N], s[N], top;

void citire()
{
    scanf("%d %d\n", &n, &m);
    for(int i=0;i<m;i++)
    {
        int x, y;
        scanf("%d %d\n", &x, &y);
        graf[x].push_back(y);
        graf[y].push_back(x);
    }
}

void afisare()
{
    printf("%d\n", nr);
    for(int i=1;i<=nr;i++)
    {
        for(int j=0;j<sol[i].size();j++)
            printf("%d ", sol[i][j]);
        printf("\n");
    }
}

int muchii(int nod, int tata)
{
    niv[nod]=niv[tata]+1;
    s[++top]=nod;
    int minim=niv[nod];
    for(int i=0;i<graf[nod].size();i++)
        {
            int fiu=graf[nod][i];
            if(fiu==tata)
                continue;
            if(niv[fiu])
            {
                minim=min(minim, niv[fiu]);
                continue;
            }

            int x=top;
            int nivel=muchii(fiu, nod);
            if(nivel>=niv[nod])
            {
                nr++;
                sol[nr].push_back(nod);
                while(top!=x)
                {
                    sol[nr].push_back(s[top]);
                    top--;
                }
            }
        minim=min(nivel, minim);
    }
    return minim;
}


int main()
{
    freopen("biconex.in", "r", stdin);
    freopen("biconex.out", "w", stdout);

    citire();
    muchii(1, 0);
    afisare();
    return 0;
}