#include <cstdio>
#define NMAX 100010
#include <vector>
#include <stack>
#include <bitset>
using namespace std;
vector <int> graf[NMAX];
vector <int> grafinvers[NMAX];
vector <int> solutie[NMAX];
bitset <NMAX> viz;
stack <int> coada;
int n,nr,m;

void read()
{
    int x,y;
    freopen("ctc.in","r",stdin);
    freopen("ctc.out","w",stdout);
    scanf("%d %d",&n,&m);
    for(int i = 0 ; i< m ; i++)
    {
        scanf("%d %d",&x,&y);
        graf[x].push_back(y);
        grafinvers[y].push_back(x);
    }
}

void parcurgere(int start)
{
    viz[start] = true;
    for(vector <int>:: iterator it = graf[start].begin(); it != graf[start].end();it++)
       if(viz[*it] == false)
            parcurgere(*it);
    coada.push(start);
}

void parcurgeregrafinvers(int start, int poz)
{
    solutie[poz].push_back(start);
    viz[start] = true;
    for(vector <int> :: iterator it = grafinvers[start].begin() ; it != grafinvers[start].end() ; it++)
        if(viz[*it] == false)
            parcurgeregrafinvers(*it,poz);

}

void afisare(int n)
{
    for(int i = 0 ; i < n ; i++)
    {
        for(vector <int>::iterator it = solutie[i].begin(); it != solutie[i].end() ; it++)
                printf("%d ",*it);
        printf("\n");
    }
}

int main()
{
    int aux;
    read();
    for(int i = 1;  i <= n ; i++)
        if(viz[i] == false)
            parcurgere(i);
    viz.reset();
    while(!coada.empty())
    {
        aux = coada.top();
        coada.pop();
        if(viz[aux] == false)
        {
            parcurgeregrafinvers(aux,nr);
            nr++;
        }
    }
    printf("%d\n",nr);
    afisare(nr);

    return 0;
}