#include<cstdio>
#include<algorithm>
#include<vector>
#include<stack>
using namespace std;
#define NMAX 100005
vector <int> v[NMAX],L[NMAX];
stack < pair<int,int> > st;
pair <int,int> p;
int n,m,x,y,nr,a[NMAX],low[NMAX];
void dfs(int s, int tata, int niv)
{
    int i;
    a[s]=niv, low[s]=niv;
    for (i=0;i<v[s].size();++i)
    {
        if (v[s][i]==tata) continue;
        if (!a[v[s][i]])
        {
            st.push(make_pair(s,v[s][i]));
            dfs(v[s][i],s,niv+1);
            if (a[s]<=low[v[s][i]])
            {
                ++nr;
                do
                {
                    p=st.top(); st.pop();
                    L[nr].push_back(p.first);
                    L[nr].push_back(p.second);
                } while (p.first!=s || p.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=1;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());
        printf("%d ",L[i][0]);
        for (j=1;j<L[i].size();++j)
            if (L[i][j]!=L[i][j-1])
                printf("%d ",L[i][j]);
        printf("\n");
    }
    return 0;
}