#include<cstdio>
#include<vector>
using namespace std;
const int MAXN = 100000;
vector <int> v,drum[MAXN + 1],rdrum[MAXN +1],comp[MAXN + 1];
int cnt;
bool viz[MAXN + 1];
void dfs(int tata)
{
    int fiu,i;
    viz[tata]=1;
    for(i=0;i<drum[tata].size();i++)
    {
        fiu=drum[tata][i];
        if(viz[fiu]==0)
        {
            dfs(fiu);
        }
    }
    v.push_back(tata);
}
void rdfs(int tata)
{
    int fiu,i;
    viz[tata]=1;
    for(i=0;i<rdrum[tata].size();i++)
    {
        fiu=rdrum[tata][i];
        if(viz[fiu]==0)
        {
            rdfs(fiu);
        }
    }
    comp[cnt].push_back(tata);
}
int main()
{
    int n,m,i,x,y;
    freopen("ctc.in","r",stdin);
    freopen("ctc.out","w",stdout);
    scanf("%d%d",&n,&m);
    for(i=1;i<=m;i++)
    {
        scanf("%d%d",&x,&y);
        drum[x].push_back(y);
        rdrum[y].push_back(x);
    }
    for(i=1;i<=n;i++)
    {
        if(viz[i]==0)
        {
            dfs(i);
        }
    }
    for(i=1;i<=n;i++)
        viz[i]=0;
   // for(i=1;i<=n;i++)
  //      printf("%d ",v[i]);
    printf("\n");
    for(i=n-1;i>=0;i--)
    {
        if(viz[v[i]]==0)
        {
            cnt++;
            rdfs(v[i]);
        }
    }
    printf("%d\n",cnt);
    for(i=1;i<=cnt;i++)
    {
        for(x=0;x<comp[i].size();x++)
            printf("%d ",comp[i][x]);
        printf("\n");
    }
    return 0;
}