#include <cstdio>

struct nod {int inf; nod *urm;} *g[100001],*sol[200001];

int st[200001],niv[100001],low[100001],tata[100001];
int viz[100001],vf;
int n,m,nr,nrsol;

int min(int x,int y)
{
    return x<y?x:y;
}

void baga(int x, int y)
{
    nod *q=new nod;
    q->inf=y;
    q->urm=g[x];
    g[x]=q;
    q=new nod;
    q->inf=x;
    q->urm=g[y];
    g[y]=q;
}

void update(int i,int j)
{
    int z1,z2;
    nrsol++;
    do
    {
        z1=st[vf];
        z2=st[vf-1];
        nod *q=new nod;
        q->inf=z1;
        q->urm=sol[nrsol];
        sol[nrsol]=q;
        q=new nod;
        q->inf=z2;
        q->urm=sol[nrsol];
        sol[nrsol]=q;
        vf-=2;
    } while(z1-j || z2-i);
}

void dfs(int x)
{
    viz[x]=1;
    niv[x]=low[x]=nr++;
    for(nod *i=g[x];i;i=i->urm)
    {
        if(!viz[i->inf])
        {
            tata[i->inf]=x;
            st[++vf]=x;
            st[++vf]=i->inf;
            dfs(i->inf);
            if(low[i->inf]>=niv[x])
                update(x,i->inf);
            low[x]=min(low[x],low[i->inf]);
        }
        else if(tata[x]!=i->inf)
            low[x]=min(low[x],niv[i->inf]);
    }
}

int main()
{
    freopen("biconex.in","r",stdin);
    freopen("biconex.out","w",stdout);
    scanf("%d%d",&n,&m);
    int x,y;
    for(int i=1;i<=m;i++)
    {
        scanf("%d%d",&x,&y);
        baga(x,y);
    }
    for(int i=1;i<=n;i++)
        if(!viz[i])
        {
            nr=1;
            dfs(i);
        }
    printf("%d\n",nrsol);
    for(int i=1;i<=nrsol;i++)
    {
        for(nod *q=sol[i];q;q=q->urm)
            viz[q->inf]=0;
        for(nod *q=sol[i];q;q=q->urm)
            if(!viz[q->inf])
            {
                viz[q->inf]=1;
                printf("%d ",q->inf);
            }
        printf("\n");
    }
}