#include <fstream>
#include <vector>
using namespace std;
ifstream in ("ctc.in");
ofstream out ("ctc.out");

const int NMax = 1e5+5;

int n,m,nrctc, Use[NMax], X[NMax],nr;
vector <int> G[NMax];
vector <int> sol[NMax];
vector <int> GT[NMax];

void DFS_I(int nod)
{
    Use[nod]=1;
    for (int i=0;i<G[nod].size();i++)
    {
        int vecin=G[nod][i];
        if (!Use[vecin])
        {
            DFS_I(vecin);
        }
    }
    nr++;
    X[nr]=nod;
}
void DFS_II(int nod)
{
    Use[nod]=0;
    for (int i=0;i<GT[nod].size();i++)
    {
        int vecin=GT[nod][i];
        if (Use[vecin])
        {
            DFS_II(vecin);
        }
    }
    sol[nrctc].push_back(nod);
}
void Read()
{
    int x,y;
    in>>n>>m;
    while (m--)
    {
        in>>x>>y;
        G[x].push_back(y);
        G[y].push_back(x);
    }
}
void Solve()
{
    for (int i=1;i<=n;i++)
    {
        if (!Use[i])
        {
            DFS_I(i);
        }
    }
    for (int i=n;i>=1;i--)
    {
        if (Use[X[i]])
        {
            nrctc++;
            DFS_II(X[i]);
        }
    }
}
void Print()
{
    out<<nrctc<<'\n';
    for (int j=1;j<=nrctc;j++)
    {
        for (int i=0;i<sol[j].size();i++)
        {
            out<<sol[j][i]<<' ';
        }
        out<<'\n';
    }
}

int main()
{
    Read();
    Solve();
    Print();
    return 0;
}