#include <vector>
#include <cstdio>
#include <string>
#include <algorithm>
#include <stack>
#include <string.h>
#define cat(c) while (c!='\n') fscanf(f,"%c",&c);
#define ct(c) while (c!='\n') scanf("%c",&c);
#define lim 100100
using namespace std;
FILE *f,*g;

vector <int> a[lim],b[lim],bt[lim];
vector <vector <int> > sol;
vector <int> con;
stack <int>S;
int ind[lim],mn[lim],in_q[lim];
int nr,n,m,i,j,cn;
int bf[lim];
int h[lim];
bool dr[255][255];
bool tk[lim]; // a fost conectat sau nu

void tare_conex(int x)
{
     int i;
     ind[x]=mn[x]=++nr;
     in_q[x]=1; S.push(x);

     for (i=0;i<a[x].size();i++)
     {
          if (ind[a[x][i]]==0)
          {
               tare_conex(a[x][i]);
               mn[x]=min(mn[x],mn[a[x][i]]);
          }
          else
               if (in_q[x])
                    mn[x]=min(mn[x],mn[a[x][i]]);
     }

     if (ind[x]==mn[x])
     {
          int nod;
          con.clear();
          cn++;
          do {
               nod=S.top(); S.pop();
               in_q[nod]=0; con.push_back(nod);
               bf[nod]=cn;
               }
          while (nod!=x);
          sol.push_back(con);
     }

}


void  fa_muchii()
{
     int i,j;

     for (i=1;i<=n;i++)
          for (j=0;j<a[i].size();j++)
               if (bf[i]!=bf[a[i][j]])
                    if (dr[bf[i]][bf[a[i][j]]]==0)
                         {
                              dr[bf[i]][bf[a[i][j]]]=1;
                              b[bf[i]].push_back(bf[a[i][j]]);
                              bt[bf[a[i][j]]].push_back(bf[i]);
                         }
}


void read()
{
     int i,x,y;
     f=fopen("ctc.in","r");
     g=fopen("ctc.out","w");

     fscanf(f,"%d%d",&n,&m);
     for (i=1;i<=m;i++)
     {
          fscanf(f,"%d%d",&x,&y);
          a[x].push_back(y);
     }
}

int X[260],Y[260];
int nx,ny,ax,rx,ry;

void  df(int x,int r)
{
     int i,y;
     h[x]=r;

     if (b[x].size()==0 && tk[x]==0)
          ax=x;

     for (i=0;i<b[x].size();i++)
          if (h[b[x][i]]!=r)
               df(b[x][i],r);


}


int main()
{

     read();

     sol.push_back(con);


    nr=0;
     for (i=1;i<=n;i++)
          if (ind[i]==0)
          {
               tare_conex(i);
          }

     fprintf(g,"%d\n",cn);
     for (i=1;i<=cn;i++,fprintf(g,"\n"))
          for (j=0;j<sol[i].size();j++)
               fprintf(g,"%d ",sol[i][j]);


     /*if (cn==1)
     {
          fprintf(g,"0");
          return 0;
     }

     fa_muchii();

     for (i=1;i<=cn;i++)
          if (bt[i].size()==0)
          {
               ax=-1;
               df(i,i);

               if (ax!=-1)
               {
                    X[++nx]=i;
                    tk[i]=1;
                    Y[++ny]=ax;
                    tk[ax]=1;
               }
          }

     rx=nx;
     ry=ny;

     for (i=1;i<=cn;i++)
     {
          if (b[i].size()==0 && tk[i]==0)
               Y[++ny]=i;
          if (bt[i].size()==0 && tk[i]==0)
               X[++nx]=i;
     }

     fprintf(g,"%d\n",max(nx,ny));


     for (i=1;i<rx;i++)
     {
          fprintf(g,"%d %d\n",sol[Y[i]][0],sol[X[i+1]][0]);
     }
     fprintf(g,"%d %d\n",sol[Y[rx]][0],sol[X[1]][0]);

     for (i=rx+1;i<=min(nx,ny);i++)
          fprintf(g,"%d %d\n",sol[Y[i]][0],sol[X[i]][0]);

     if (nx>ny)
          for (;i<=nx;i++)
               fprintf(g,"%d %d\n",sol[X[1]][0],sol[X[i]][0]);
     else
          for (;i<=ny;i++)
               fprintf(g,"%d %d\n",sol[Y[i]][0],sol[X[1]][0]);
     */

	return 0;
}