#include<stdio.h>
#include<vector>
using namespace std;
#define nmax 100005
int n, m, i, x, y, sf, ncomp;
vector <int> ma[nmax], comp[nmax];
vector <int> ::iterator it;
int st[nmax], niv[nmax], t[nmax], dfn[nmax];


void citire()
{
    scanf("%ld %ld",&n,&m);
    for (i=1;i<=m;i++)
    {
        scanf("%ld %ld",&x,&y);
        ma[x].push_back(y); ma[y].push_back(x);
    }
}

void dfs(int x)
{
    vector <int> ::iterator it;
    int y;
    niv[x]=niv[t[x]]+1; st[++sf]=x;
    dfn[x]=niv[x];
    for (it=ma[x].begin();it!=ma[x].end();it++)
    {
        y=*it;
        if ((niv[y]>0)&&(y!=t[x])&&(niv[y]<dfn[x]))
            dfn[x]=niv[y];
        if (niv[y]==0)
        {
            t[y]=x;
            dfs(y);
            if (dfn[y]<dfn[x])
                dfn[x]=dfn[y];
            if (dfn[y]>=niv[x])
            {
                ncomp++;
                while(st[sf+1]!=y)
                {
                    comp[ncomp].push_back(st[sf]);
                    sf--;
                }
                comp[ncomp].push_back(x);
            }
        }
    }
}

void afisare()
{
    printf("%ld\n",ncomp);
    for (i=1;i<=ncomp;i++)
    {
        for (it=comp[i].begin();it!=comp[i].end();it++)
            printf("%ld ",*it);
        printf("\n");
    }
}

int main()
{
    freopen("biconex.in","r",stdin);
    freopen("biconex.out","w",stdout);
    citire();
    for (i=1;i<=n;i++)
        if (niv[i]==0)
            dfs(i);
    afisare();
    return 0;
}