#include <iostream>
#include <fstream>
#include <vector>
#include <stack>
#include <algorithm>
#define nmax 100003
using namespace std;
ifstream f("ctc.in");
ofstream g("ctc.out");
int n,m, viz[nmax], nrc;
vector <int> v[nmax], vt[nmax], sol[nmax];
stack <int> s;

void citire()
{
    int i,x,y;
    f>>n>>m;
    for(i=0; i<=m; i++)
    {
        f>>x>>y;
        v[x].push_back(y);
        vt[y].push_back(x);
    }
}

void adanc(int nod)
{
    int next, i;
    viz[nod]=1;
    for(i=0; i<v[nod].size(); i++)
    {
        next=v[nod][i];
        if(!viz[next])
            adanc(next);
    }
    s.push(nod);
}

void adanct(int nod)
{
    int next, i;
    viz[nod]=0;
    sol[nrc].push_back(nod);
    for(i=0; i<vt[nod].size(); i++)
    {
        next=vt[nod][i];
        if(viz[next])
            adanct(next);
    }
}

int main()
{
    citire();
    int nod,i,j;
    for(i=1; i<=n; i++)
    if(viz[i]==0)
        adanc(i);
    while(!s.empty())
    {
        nod=s.top();
        s.pop();
        if(viz[nod])
        {
            nrc++;
            adanct(nod);
        }
    }
    g<<nrc<<"\n";
    for(i=1; i<=nrc; i++)
    {sort(sol[i].begin(), sol[i].end());
        for(j=0; j<sol[i].size(); j++)
        g<<sol[i][j]<<" ";
            g<<"\n";}
    f.close();
    g.close();
    return 0;
}