#include<cstdio>
#include<vector>
#include<iostream>
#include<stack>
#include<algorithm>
using namespace std;
#define NMAX 100005
vector <int> v[NMAX],L[NMAX];
int n,m,x,y,nr;
int a[NMAX],low[NMAX];
pair <int,int> c;
stack < pair<int,int>   > stiva;
void dfs(int s, int parent, int niv)
{
    int i;
    a[s]=niv; low[s]=niv;
    for (i=0;i<v[s].size();++i) {
        if (v[s][i] == parent)
            continue;
        if (!a[v[s][i]]){
            stiva.push(make_pair(s,v[s][i]));
            dfs(v[s][i],s,niv+1);
            if (a[s] <= low[v[s][i]]) {
                // pornirea din s pe muchia spre v[s][i] ne provoaca o componenta biconexa
                // scoatem din stiva toate muchiile inclusiv pana la muchia s-v[s][i]
                ++nr;
                do {
                    c = stiva.top();
                    stiva.pop();
                    L[nr].push_back(c.first);
                    L[nr].push_back(c.second);
                } while (c.first!=s || c.second!=v[s][i]);
            }
        }
        low[s] = min(low[s], low[v[s][i]]);

    }
}
int main()
{
    int i,j;
    freopen("biconex.in","r",stdin);
    freopen("biconex.out","w",stdout);
    scanf("%d%d",&n,&m);
    for (i=0;i<m;++i)
    {
        scanf("%d%d",&x,&y);
        v[x].push_back(y);
        v[y].push_back(x);
    }
    dfs(1,0,1);
    printf("%d\n",nr);
    for (i=1;i<=nr;++i)
    {
        sort(L[i].begin(),L[i].end());
        cout<<L[i][0]<<' ';

        for (j=1;j<L[i].size();++j)
            if (L[i][j]!=L[i][j-1])
                cout<<L[i][j]<<' ';
        cout<<'\n';
    }
    return 0;
}