#include <cstdio>
#include <vector>
#include <bitset>

using namespace std;

const int nmx = 100002;

int n,m,total,f[2*nmx];
vector <int> g[nmx], l;
bitset <nmx> viz;

void citire(){
    scanf("%d %d", &n, &m);
    int nod1,nod2;
    for(int i = 1; i <= m; ++i){
        scanf("%d %d", &nod1, &nod2);
        g[nod1].push_back(nod2);
    }
}

void parcurgere(int nod){
    viz[nod] = true;
    for(vector<int>::iterator it = g[nod].begin(); it != g[nod].end(); ++it)
        if(not viz[*it])
            parcurgere(*it);
    l.push_back(nod);
}

void sortaret(){
    for(int i = 1; i <= n; ++i)
        if(not viz[i])
            parcurgere(i);
}

void adaugare(int nod, int &nr){
    ++ nr;
    viz[nod] = true;
    f[++f[0]] = nod;
    for(vector<int>::iterator it = g[nod].begin(); it != g[nod].end(); ++it)
        if(not viz[*it])
            adaugare(*it,nr);
}

void componente(){
    viz.reset();
    for(vector<int>::iterator it = l.begin(); it != l.end(); ++it)
       if(not viz[*it]){
           ++ total;
           int nr = 0;
           adaugare(*it,nr);
           f[++f[0]] = nr;
       }
}

void afisare(){
    printf("%d\n", total);
    for(int i = f[0]; i; --i){
        int nr = f[i];
        while(nr){
            printf("%d ", f[--i]);
            -- nr;
        }
        printf("\n");
    }
}

int main(){
    freopen("ctc.in", "r", stdin);
    freopen("ctc.out", "w", stdout);
    citire();
    sortaret();
    componente();
    afisare();
    //for(vector<int>::reverse_iterator it = l.rbegin(); it != l.rend(); ++it)
      //  printf("%d ", *it);
    return 0;
}