#include <cstdio>
#include <deque>
#include <vector>
#include <algorithm>
using namespace std;
deque<int> st;
vector<int> g[100005];
struct Nod
{
    int disc,low;
} v[100005];
vector<int> sol[100005];
bool viz[100005];
bool critic[100005];
struct Solutie
{
    int x,y;
};
vector<Solutie> muchie;
int nr,k;
void dfs(int nod, int root, int tata)
{
    st.push_back(nod);
    viz[nod]=1;
    int fiu=0;
    for(int i=0; i<g[nod].size(); i++){
        if(viz[g[nod][i]]==0){
            v[g[nod][i]].disc=v[nod].disc+1;
            v[g[nod][i]].low=v[nod].disc+1;
            dfs(g[nod][i], root, nod);
            v[nod].low=min(v[nod].low, v[g[nod][i]].low);
            fiu++;
        }
        else{
            if(g[nod][i]!=tata)
                v[nod].low=min(v[nod].low, v[g[nod][i]].disc);
            continue;
        }
        if(v[g[nod][i]].low>v[nod].disc)
            muchie.push_back({g[nod][i], nod});
        if(v[g[nod][i]].low>=v[nod].disc){
            ++k;
            int x;
            do{
                x=st.back();
                sol[k].push_back(st.back());
                st.pop_back();
            }while(x!=g[nod][i]);
            sol[k].push_back(nod);
            if(nod!=root)
                critic[nod]=1;
        }
    }
    if(nod==root && fiu>1)
        critic[nod]=1;
}
int main()
{   freopen("biconex.in", "r", stdin);
    freopen("biconex.out", "w", stdout);
    int n,m,i,x,y,j,p=1;
    scanf("%d%d", &n, &m);
    for(i=1; i<=m; i++){
        scanf("%d%d", &x, &y);
        g[x].push_back(y);
        g[y].push_back(x);
    }
    for(i=1; i<=n; i++)
        if(viz[i]==0){
            v[i].disc=v[i].low=1;
            dfs(i, i, 0);
        }
    if(p==1){
        printf("%d\n", k);
        for(i=1; i<=k; i++){
            printf("%d ", sol[i].size());
            for(j=0; j<sol[i].size(); j++)
                printf("%d ", sol[i][j]);
            printf("\n");
        }
    }
    else{
        if(p==2){
            int nr=0;
            for(i=1; i<=n; i++)
                nr+=critic[i];
            printf("%d\n", nr);
            for(i=1; i<=n; i++)
                if(critic[i]==1)
                    printf("%d ", i);
        }
        else{
            printf("%d\n", muchie.size());
            for(i=0; i<muchie.size(); i++)
                printf("%d %d\n", muchie[i].x, muchie[i].y);
        }
    }
    return 0;
}