#include <fstream>
#include <iostream>
#include <vector>
#include <stack>

using namespace std;

ifstream fin("ctc.in");
ofstream fout("ctc.out");

int n,m,x,y;
vector <int >G[101],CTC[101];
int viz[101],disc[101],lowlink[101],nr=1,nrc;
stack <int> S;
void citire()
{
    fin>>n>>m;
    for(int i=1; i<=m; i++)
    {
        fin>>x>>y;
        G[x].push_back(y);
    }
}

void dfs(int nod)
{
    viz[nod]=1;
    disc[nod]=nr;
    lowlink[nod]=disc[nod];
    nr++;
    S.push(nod);
    for(auto &x:G[nod])
    {
        if(viz[x]==0)
        {
            dfs(x);
            lowlink[nod]=min(lowlink[x],lowlink[nod]);
        }
        else if(viz[x]==1)
            lowlink[nod]=min(lowlink[nod],disc[x]);
    }

    if(disc[nod]==lowlink[nod])
    {
        nrc++;
        while(S.top()!=nod)
        {
            CTC[nrc].push_back(S.top());
            viz[S.top()]=2;S.pop();
        }
        CTC[nrc].push_back(S.top());
        viz[S.top()]=2; S.pop();
    }
}

void tarjan()
{
    nr=1;
    for(int i=1; i<=n; i++)
    {
        if(viz[i]==0)
            dfs(i);
    }
    fout<<nrc<<"\n";
     for(int i=1;i<=nrc;i++,fout<<"\n")
        for(auto &x:CTC[i])
            fout<<x<<" ";
}

int main()
{
    citire();
    tarjan();
    return 0;
}