#include <stdio.h>
#include <stdlib.h>
#include <iostream>
#define nmax 100000
#define inf 0x3f3f3f3f
using namespace std;
FILE *fin,*fout;
int n,m,low[nmax+5],disc[nmax+5],time=0,gg=0,st[nmax+5],nr_sol=0;
bool viz[nmax+5];
struct nod
{
    int info;
    nod *urm;
}*v[nmax+5],*c,*e[nmax+5],*sol[nmax+5];
int minv(int a, int b)
{
    return a<b?a:b;
}
void tarjan(int k)
{
    time++;
    low[k]=disc[k]=time;
    viz[k]=1;
    nod *d=v[k];
    st[++gg]=k;
    int here=gg;
    while(d->urm)
    {
        d=d->urm;
        if(!viz[d->info])
        {
            tarjan(d->info);
            low[k]=minv(low[k],low[d->info]);
        }
        else
        low[k]=minv(low[k],disc[d->info]);
    }
    if(disc[k]==low[k])
    {
        nr_sol++;
        for(;gg>=here;gg--)
            if(!sol[nr_sol]->urm)
            {
                c=new nod;
                c->info=st[gg];
                c->urm=0;
                sol[nr_sol]->urm=c;
                e[nr_sol]=c;
                low[st[gg]]=disc[st[gg]]=inf;
            }
            else
            {
                c=new nod;
                c->info=st[gg];
                c->urm=0;
                e[nr_sol]->urm=c;
                e[nr_sol]=c;
                low[st[gg]]=disc[st[gg]]=inf;
            }
    }
}
int main()
{
    int x,y,z;
    fin=fopen("ctc.in","r");
    fout=fopen("ctc.out","w");
    fscanf(fin,"%d %d",&n,&m);
    for(int i=1;i<=n;i++)
    {
        v[i]=new nod;
        v[i]->info=i;
        v[i]->urm=0;
        sol[i]=new nod;
        sol[i]->info=i;
        sol[i]->urm=0;
    }
    for(int i=1;i<=m;i++)
    {
        fscanf(fin,"%d %d",&x,&y);
        if(!v[x]->urm)
        {
            c=new nod;
            c->info=y;
            c->urm=0;
            v[x]->urm=c;
            e[x]=c;
        }
        else
        {
            c=new nod;
            c->info=y;
            c->urm=0;
            e[x]->urm=c;
            e[x]=c;
        }
    }
    for(int i=1;i<=n;i++)
    if(!viz[i])
    {gg=0;tarjan(i);}
    fprintf(fout,"%d\n",nr_sol);
    for(int i=1;i<=nr_sol;i++)
    {
        c=sol[i];
        while(c->urm)
        {
            c=c->urm;
            fprintf(fout,"%d ",c->info);
        }
        fprintf(fout,"\n");
    }
    return 0;
}