#include <bits/stdc++.h>

using namespace std;
ifstream in("ctc.in");
ofstream out("ctc.out");
const int nx = 100001;
bitset < nx > viz;
vector < int > v[nx];
vector < int > w[nx];
vector < int > c[nx];
deque < int > s;
int n,m,i,j,k;
void srt (int nod)
{
    viz.set(nod);
    for(vector < int > :: iterator it = v[nod].begin(); it!=v[nod].end(); it++)
        if(!viz.test(*it))
            srt(*it);
    s.push_front(nod);
}
void dfs (int nod)
{
    viz.reset(nod);
    c[k].push_back(nod);
    for(vector < int > :: iterator it = w[nod].begin(); it!=w[nod].end(); it++)
        if(viz.test(*it))
            dfs(*it);
}
int main()
{
    in>>n>>m;
    for(;m;m--)
    {
        in>>i>>j;
        v[i].push_back(j);
        w[j].push_back(i);
    }
    for(int i=1; i<=n; i++)
        if(!viz.test(i))
            srt(i);
    for(deque < int > :: iterator it = s.begin(); it!=s.end(); it++)
        if(viz.test(*it))
        {
            ++k;
            dfs(*it);
        }
    out<<k<<'\n';
    for(int i=1; i<=n; i++)
    {
        for(vector < int > :: iterator it = c[i].begin(); it!=c[i].end(); it++)
            out<<*it<<' ';
        out<<'\n';
    }
    return 0;
}