#include<stdio.h>
#include<vector>
#define M 100005
 
using namespace std;
 
int n,m,niv[M],c[M],viz[M],nrs,nr;
vector<int> a[M],sol[M];

FILE *f=fopen("biconex.in","r");
FILE *g=fopen("biconex.out","w");
struct Graf
{
    int x,y;
}s[M];
 
void citire()
{
    fscanf(f,"%d%d",&n,&m);
    int x,y;
    for(int i=1;i<=m;++i)
    {
        fscanf(f,"%d%d",&x,&y);
        a[x].push_back(y);
    }
}
 
void add(int x,int y)
{
    int xi,yi;
    ++nrs;
    do
    { 
		xi=s[nr].x;
        yi=s[nr--].y;
        sol[nrs].push_back(yi);
    }
	while(xi!=x||yi!=y);
    sol[nrs].push_back(x);
}
 
void dfs(int nod,int tata)
{
    niv[nod]=niv[tata]+1;
    c[nod]=niv[nod];
    viz[nod]=1;
    for(int i=0;i<a[nod].size();++i)
    {
        int x=a[nod][i];
        if(!viz[x])
        {
            s[++nr].x=nod;
            s[nr].y=x;
            dfs(x,nod);
            if(c[x]<c[nod])
                c[nod]=c[x];
            if(c[x]>=niv[nod])
                add(nod,x);
        }
        else if(tata!=x&&c[x]<c[nod])
            c[nod]=c[x];
    }
}
 
int main()
{
    citire();
    dfs(1,0);
    fprintf(g,"%d\n",nrs);
    for(int i=1;i<=nrs;++i)
    {
        for(int j=0;j<sol[i].size();++j)
            fprintf(g,"%d ",sol[i][j]);
        fprintf(g,"\n");
    }
    return 0;
}