#include <bits/stdc++.h>
#define DIM 100010
using namespace std;
ifstream fin("biconex.in");
ofstream fout("biconex.out");
int n,m,i,p,k,j,cnt,comp,nod,vecin,tata,x,y;
int nc[DIM],low[DIM],niv[DIM],sol[DIM];
stack<int> st;
bitset<DIM> f;
vector<int> L[DIM],c[DIM];
void dfs(int nod,int tata,int nivel) {
    f[nod]=1;
    low[nod]=niv[nod]=nivel;
    st.push(nod);
    for (int i=0;i<L[nod].size();i++) {
        int vecin=L[nod][i];
        if (vecin==tata)
            continue;
        if (f[vecin]==1)
            low[nod]=min(low[nod],niv[vecin]);
        else {
            dfs(vecin,nod,nivel+1);
            low[nod]=min(low[nod],low[vecin]);
            if (low[vecin]>=niv[nod]) { ///muchia nod-vecin formeaza componenta biconexa
                nc[nod]++;
                comp++;
                do {
                    x=st.top();
                    c[comp].push_back(x);
                    st.pop();
                } while (x!=vecin);
                c[comp].push_back(nod);
            }
        }
    }
}
int main() {
    fin>>n>>m;
    for (i=1;i<=m;i++) {
        fin>>x>>y;
        L[x].push_back(y);
        L[y].push_back(x);
    }
    dfs(1,0,1);
    fout<<comp<<"\n";
    for (i=1;i<=comp;i++) {
        for (j=0;j<c[i].size();j++)
            fout<<c[i][j]<<" ";
        fout<<"\n";
    }
    return 0;
}