#include <iostream>
#include<fstream>
using namespace std;
ifstream f("ctc.in");
ofstream g("ctc.out");
int a[101][101];
int s[101];
int main()
{
   int n,m,c=0,i,j,k;
   cin>>n>>m;
   while(m--)
   {
       cin>>i>>j;
       a[i][j]=1;
   }
  //matricea drumurilor
   for(k=1;k<=n;k++)
    for(i=1;i<=n;i++)
     for(j=1;j<=n;j++)
        if(a[i][k]*a[k][j]==1)
              a[i][j]=1;

      //intersectie
for(i=1;i<=n;i++)
{
    if(s[i]==0){c++;s[i]=c;}


    for(k=1;k<=n;k++)
        if(a[k][i]==1 && a[i][k]==1)
            s[k]=c;
}
cout<<c;
cout<<endl;
for(i=1;i<=c;i++){
    for(j=1;j<=n;j++)
      if(s[j]==i)cout<<j<<" ";
      cout<<endl;

}





    return 0;
}