#include <fstream>
#include <vector>
#include <bitset>
using namespace std;
ifstream fin ("ctc.in");
ofstream fout ("ctc.out");
bitset <100001> viz;
vector <int> s,v[1000001];
vector <vector <int>> sol;
int n,m,i,j,x,y,k,nr,niv[1000001],stiva[1000001],low[1000001];
void dfs (int nod,int t,int nivel)
{
    viz[nod]=1;
    niv[nod]=low[nod]=nivel;
    stiva[++k]=nod;
    for (int i=0; i<v[nod].size (); i++)
    {
        int vecin=v[nod][i];
        if (viz[vecin])
            low[nod]=min (low[nod],low[vecin]);
        else
        {
            dfs (vecin,nod,nivel+1);
            low[nod]=min (low[nod],low[vecin]);
            if (niv[nod]<low[vecin])
            {
                s.clear ();
                do
                {
                    nr=stiva[k];
                    s.push_back (nr);
                    k--;
                }
                while (nr!=vecin);
                sol.push_back (s);
            }
        }
    }
    if (nod==1)
    {
        s.clear ();
        while (k>0)
            s.push_back (stiva[k--]);
        sol.push_back (s);
    }
}
int main()
{
    fin>>n>>m;
    for (i=1; i<=m; i++)
    {
        fin>>x>>y;
        v[x].push_back (y);
    }
    dfs (1,0,1);
    fout<<sol.size ()<<"\n";
    for (i=0; i<sol.size (); i++)
    {
        for (j=0; j<sol[i].size (); j++)
            fout<<sol[i][j]<<" ";
        fout<<"\n";
    }
    return 0;
}