#include<iostream>
#include<fstream>
int viz[100];
int a[100][100];
int n, m, c=0;
using namespace std;
ifstream f("ctc.in");
ofstream g("ctc.out");

void df(int i)
{  int j;
    viz[i]=c; 
    for (j=1; j<=n; j++) if (viz[j]==0 && a[j][i]==1) df(j);
}
int main ()
{ int i, p, q;
    f>>n;
    f>>m;
    for (i=1; i<=m; i++) 
    {f>>p>>q;
        a[p][q]=1;// a[q][p]=1;
    }
    
	
    for (i=1; i<=n; i++)  
        if (viz[i]==0)  {c++; df(i); }
    int j;
    g<<c<<endl;
    for (i=1; i<=c; i++) {
        
        for(j=1;j<=n;j++)if(viz[j]==i) g <<j<<" "; 
        g<<endl;
    }
    return 0;
}