#include <bits/stdc++.h>

using namespace std;
ifstream f("biconex.in");
ofstream g("biconex.out");
int n,m,nr,x,y;
int dfn[100001],low[100001];
bool viz[100001];
vector<vector<int>> a(100001,vector<int>()),componente(100001,vector<int>());
stack<int> S;
void Citire()
{
    f>>n>>m;
    for(int i=1;i<=m;++i)
    {
        f>>x>>y;
        a[x].push_back(y);
        a[y].push_back(x);
    }
    f.close();
}


void DFS(int nod, int parinte, int nivel)
{
    viz[nod] = true;
    dfn[nod] = low[nod] = nivel;
    S.push(nod);
    for(vector<int>::iterator it=a[nod].begin();it!=a[nod].end();++it)
    {
        if(viz[*it]) low[nod] = min(low[nod],dfn[*it]);
        else
        {
            DFS(*it,nod,nivel+1);
            low[nod] = min(low[nod],low[*it]);
            if(low[*it] >= dfn[nod])
            {
                ++nr;
                componente[nr].push_back(nod);
                do{
                    x = S.top();
                    componente[nr].push_back(x);
                    S.pop();
                }while(x!=*it);
            }
        }
    }
}

void Afisare()
{
    g<<nr<<'\n';
    for(int i=1;i<=n;++i)
    {
        for(vector<int>::iterator it=componente[i].begin();it!=componente[i].end();++it)
            g<<*it<<" ";
        g<<'\n';
    }
}

int main()
{
    Citire();
    DFS(1,-1,1);
    Afisare();
    return 0;
}