#include <bits/stdc++.h>

using namespace std;
ifstream f("biconex.in");
ofstream g("biconex.out");
int niv[100005],l[100005],tata[100005],q;
bool viz[100005];
vector <int> v[100005];
stack <pair <int,int > > deq;
vector <int> comp[100005];
void dfs(int x,int nivel)
{
    int i;
    viz[x]=1;
    niv[x]=nivel;
    l[x]=niv[x];
    for (i=0;i<v[x].size();i++)
    {
        int nod=v[x][i];
        if (viz[nod]==0)
        {
            tata[nod]=x;
            deq.push({x,nod});
            dfs(nod,nivel+1);
            if (l[nod]<l[x])
            {
                l[x]=l[nod];
            }
            if (l[nod]>=niv[x])
            {
                q++;
                int ok=1;
                while (ok==1)
                {
                    int x2=deq.top().first;
                    int y2=deq.top().second;
                    comp[q].push_back(x2);
                    comp[q].push_back(y2);

                    deq.pop();

                    if (x2==x||y2==nod)
                    {
                        break;
                    }
                }
            }
        }
        else
        {
            if (tata[x]!=nod&&l[x]>niv[nod])
            {
                l[x]=niv[nod];
            }
        }
    }

}
int n,m,x,y,i,j;
int main()
{
    f>>n>>m;
    for (i=1;i<=m;i++)
    {
        f>>x>>y;
        v[x].push_back(y);
        v[y].push_back(x);
    }
    for (i=1;i<=n;i++)
    {
        if (viz[i]==0)
        {
            dfs(1,0);
        }
    }
    g<<q<<'\n';
    for (i=1;i<=q;i++)
    {
        sort (comp[i].begin(),comp[i].end());
        g<<comp[i][0]<<" ";
        for (j=1;j<comp[i].size();j++)
        {
            if (comp[i][j]!=comp[i][j-1])
            {
                g<<comp[i][j]<<" ";
            }
        }
        g<<'\n';
    }
    return 0;
}