#include <fstream>
#include <vector>
#include <queue>

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

vector<int> v[100001],vv[100001],q;
int n,m,i,j,k,l,s[100001],x,y,nr;

void dfs(int nod)
{
    for (vector<int>::iterator it = v[nod].begin(); it != v[nod].end(); it ++)
    {
        if (s[*it]==0)
        {
            s[*it]=1;
            dfs(*it);
            q.push_back(*it);
        }
    }
}

void dfsv(int nod, bool afis)
{
    for (vector<int>::iterator it = vv[nod].begin(); it != vv[nod].end(); it ++)
    {
        if (s[*it]==1)
        {
            s[*it]=2;
            if (afis == true)
                fout<<*it<<" ";
            dfsv(*it,afis);
        }
    }
}

int main()
{
    fin>>n>>m;
    for (i=1;i<=m;i++)
    {
        fin>>x>>y;
        v[x].push_back(y);
        vv[y].push_back(x);
    }
    for (i=1;i<=n;i++)
    {
        if (s[i]==0)
        {
            s[i]=1;
            dfs(i);
            q.push_back(i);
            while (q.empty() == false)
            {
                if (s[q.back()]==1)
                {
                    s[q.back()]=2;
                    dfsv(q.back(),false);
                    nr++;
                }
                q.pop_back();
            }
        }
    }
    fout<<nr<<"\n";
    for (i=1;i<=n;i++)
        s[i]=0;
    for (i=1;i<=n;i++)
    {
        if (s[i]==0)
        {
            s[i]=1;
            dfs(i);
            q.push_back(i);
            while (q.empty() == false)
            {
                if (s[q.back()]==1)
                {
                    s[q.back()]=2;
                    fout<<q.back()<<" ";
                    dfsv(q.back(),true);
                    fout<<"\n";
                }
                q.pop_back();
            }
        }
    }
    return 0;
}