#include <fstream>
#include <vector>
#include <bitset>
using namespace std;
ifstream fin ("ctc.in");
ofstream fout ("ctc.out");
const int nmax=100005;
vector <int> a[nmax],b[nmax],s[nmax];
vector<int>::iterator it;
bitset<nmax>viz;
int i,j,n,m,x,y,k,tsort[nmax];
void citire ()
{
     fin>>n>>m;
     for (i=1;i<=m;i++)
     {
         fin>>x>>y;
         a[x].push_back(y);
         b[y].push_back(x);
         }
     }
void dfs(int nod)
{
     
    for(vector<int>::iterator it=a[x].begin();it!=a[x].end();it++)
        if (!viz[*it])
        {
                      viz[*it]=1;
                      dfs(*it);
                      }
    tsort[++k]=nod;
     }
void dfst(int nod)
{
     s[k].push_back(nod);
     for (vector<int>::iterator it=b[nod].begin();it!=b[nod].end();it++)
     if (!viz[*it])
     {
                   viz[*it]=1;
                   dfst(*it);
                   }
     }
int main ( )
{
    citire ();
    for (i=1;i<=n;i++)
    if (!viz[i])
    {
                viz[i]=1;
                dfs(i);
                }
    viz=0;
    k=0;
    for (i=n;i;--i)
    if(!viz[tsort[i]])
    {
    viz[tsort[i]]=1; 
    k++; 
    dfst(tsort[i]);}
    
    fout<<"\n"<<k;
for (i=1;i<=k;++i)
{ fout<<"\n";
for (vector<int>::iterator it=s[i].begin();it!=s[i].end();it++)
fout<<*it; }
return 0;
}